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High 5 Games Software Engineer Interview Guide

High 5 Games Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

A Software Engineer at High 5 Games plays a pivotal role in creating, optimizing, and deploying highly engaging interactive gaming experiences. As a leading independent casino games provider, the company delivers content across land-based, online, and social gaming channels. Engineers here do not just write code; they build the foundational systems, game engines, and mathematical integrations that power real-time experiences for millions of active players globally. This position is highly collaborative, bridging the gap between artistic vision, mathematical models, and robust systems engineering. You will work closely with game designers, artists, and mathematicians to translate complex game mechanics into high-performance software.

This guide is scoped to a Software Engineer candidate at High 5 Games.

Focus areas

  • C++
  • Programming Problem Solving
  • Data Structures (Hash Maps)

The High 5 Games interview process

High 5 Games candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Initial Screening Call

A conversation with an HR representative focusing on your background, career goals, and alignment with the role.

What to demonstrate

  • A conversation with an HR representative focusing on your background, career goals, and alignment with the role
  • Depth in C++

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Evaluation

This phase may include a technical phone screen or a take-home coding assignment to demonstrate your coding standards.

What to demonstrate

  • This phase may include a technical phone screen or a take-home coding assignment to demonstrate your coding standards
  • Depth in C++

How to prepare

  • Answer aloud and timed: How does memory management differ between a garbage-collected language like Java and a manual language like C++?
  • Answer aloud and timed: Explain the concept of object-oriented programming (OOP) polymorphism and how it is implemented at runtime.

Virtual or Onsite Interviews

Meet with engineering managers, peer developers, and occasionally executive leadership to discuss your resume and previous projects.

What to demonstrate

  • Meet with engineering managers, peer developers, and occasionally executive leadership to discuss your resume and previous projects
  • Depth in C++

How to prepare

  • Answer aloud and timed: What is a deadlock, and what strategies can you use to prevent it in a multi-threaded application?
  • Answer aloud and timed: Design and implement a simple, console-based dice game using C++ that simulates player turns and tracks scores.

Where candidates lose points

Clarify the Role Focus

Because High 5 Games hires for various engineering needs, ensure you understand whether your target role is focused on low-level engine development (C++), backend systems (Java), or front-end game client development (JavaScript). Tailor your preparation accordingly.

Test Your Interview Setup

If you are participating in a virtual interview, ensure your video, audio, and screen-sharing tools are fully tested beforehand to avoid technical disruptions during coding walk-throughs.

Prepare to Walk Through Your Code

If you complete a take-home coding challenge, be ready to defend your architectural decisions. Interviewers may ask you to add a small feature to your code live during the interview to see how adaptable your design is.

Questions & practice

How is a hash map implemented under the hood, and how are collisions handled?

Medium · Computer Science Fundamentals & Core Tri

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

What are the differences between a process and a thread, and what happens if a thread dies unexpectedly?

Medium · Computer Science Fundamentals & Core Tri

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

How does memory management differ between a garbage-collected language like Java and a manual language like C+

Medium · Computer Science Fundamentals & Core Tri

How does memory management differ between a garbage-collected language like Java and a manual language like C++?

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

Explain the concept of object-oriented programming (OOP) polymorphism and how it is implemented at runtime.

Medium · Computer Science Fundamentals & Core Tri

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

What is a deadlock, and what strategies can you use to prevent it in a multi-threaded application?

Medium · Computer Science Fundamentals & Core Tri

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

Write an algorithm to calculate the probability of a specific outcome in a simplified slot machine or card gam

Medium · Coding & Game Logic Challenges

Write an algorithm to calculate the probability of a specific outcome in a simplified slot machine or card game.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

How would you structure a game loop to handle real-time rendering and user input updates?

Medium · Coding & Game Logic Challenges

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Implement a function to find the shortest path or valid moves on a grid-based game board.

Medium · Coding & Game Logic Challenges

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

How do you ensure thread safety when multiple users are updating a shared global state simultaneously?

Medium · System Design & Concurrency

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

Explain why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

  1. Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
  2. For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
  3. Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
  4. Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

  • 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
  • A dashboard runs this for 40 owners in one page load. What changes about the design?

Replace offset paging on the resource feed with keyset

Easy · keyset pagination · composite index · sort order

resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.

Approach

  1. Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
  2. Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
  3. Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
  4. Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.

Follow-up

  • The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
  • Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?

Design and implement a simple, console-based dice game using C++ that simulates player turns and tracks scores

Medium · Coding & Game Logic Challenges

Design and implement a simple, console-based dice game using C++ that simulates player turns and tracks scores.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

How would you design a backend system to manage real-time multiplayer game states across thousands of concurre

Medium · System Design & Concurrency

How would you design a backend system to manage real-time multiplayer game states across thousands of concurrent users?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

What caching strategies would you implement to reduce database load for frequently accessed player profile dat

Medium · System Design & Concurrency

What caching strategies would you implement to reduce database load for frequently accessed player profile data?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Describe how you would design an API to handle secure in-game transactions and reward distributions.

Medium · System Design & Concurrency

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

One log partition stops advancing while the others drain

Easy · poison message · head-of-line blocking · consumer lag

Search results for a subset of tenants are hours stale; the rest are current. The projection consumer reports lag of zero on 15 of 16 partitions and 400,000 on one. Its error rate is flat and its CPU is idle. outbox_event has no pending rows older than a second, so the relay has published everything it holds. Identify the mechanism, give the ordered checks, and state what you do in the first ten minutes versus what you change permanently.

Approach

  1. Read the lag distribution first. A slow consumer lags everywhere; zero on fifteen partitions and 400,000 on one is not throughput. Idle CPU on the stuck partition means the consumer is not advancing its offset at all, which points at one message it cannot get past rather than at a rate problem.
  2. Exonerate the producer before touching the consumer. No pending outbox rows older than a second means the relay published, so the event exists in the log. This separates never sent from sent and never applied, which are different code paths and usually different owners.
  3. Read the message at the stuck offset and the handler's log lines for its event_id. A flat error rate with no progress has two explanations and you must distinguish them: the handler is throwing and the retry loop is swallowing it, or the handler is blocking on something and never returning. Idle CPU with no error lines favours the second.
  4. Mitigate before diagnosing further. Move the offending event to a dead-letter store and commit the offset past it. Adding consumers does nothing here, because a partition is consumed by exactly one member of the group, and the blast radius is every aggregate hashed to that partition, not only the aggregate that produced the bad event.

Follow-up

  • The dead-lettered event carried aggregate_version 7 and the projection had applied 6. What must the replay do differently if 8 and 9 landed in the meantime?
  • How do you show staleness to the user while the partition is behind, given the API already returns the projection's watermark?

Suggested practice checklist

Built from the rounds and topics High 5 Games candidates report.

Day 1 — Map the High 5 Games loop

  • Write out the reported sequence: Initial Screening Call, Technical Evaluation, Virtual or Onsite Interviews.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work C++

  • Spend the session on C++, which High 5 Games candidates report being tested on.
  • Write one worked example in C++ and time yourself on it.

Deliverable: One timed worked example in C++.

Day 3 — Work Programming Problem Solving

  • Spend the session on Programming Problem Solving, which High 5 Games candidates report being tested on.
  • Write one worked example in Programming Problem Solving and time yourself on it.

Deliverable: One timed worked example in Programming Problem Solving.

Day 4 — Work Data Structures (Hash Maps)

  • Spend the session on Data Structures (Hash Maps), which High 5 Games candidates report being tested on.
  • Write one worked example in Data Structures (Hash Maps) and time yourself on it.

Deliverable: One timed worked example in Data Structures (Hash Maps).

Day 5 — Answer out loud: Computer Science Fundamentals & Core Trivia

  • Answer aloud, timed: How is a hash map implemented under the hood, and how are collisions handled?
  • Answer aloud, timed: What are the differences between a process and a thread, and what happens if a thread dies unexpectedly?

Deliverable: Spoken answers to 2 reported Computer Science Fundamentals & Core Trivia question(s), under time.

Day 6 — Answer out loud: Coding & Game Logic Challenges

  • Answer aloud, timed: Design and implement a simple, console-based dice game using C++ that simulates player turns and tracks scores.
  • Answer aloud, timed: Write an algorithm to calculate the probability of a specific outcome in a simplified slot machine or card game.

Deliverable: Spoken answers to 2 reported Coding & Game Logic Challenges question(s), under time.

Day 7 — Answer out loud: System Design & Concurrency

  • Answer aloud, timed: How would you design a backend system to manage real-time multiplayer game states across thousands of concurrent users?
  • Answer aloud, timed: What caching strategies would you implement to reduce database load for frequently accessed player profile data?

Deliverable: Spoken answers to 2 reported System Design & Concurrency question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Why are you interested in working at High 5 Games, and what is your favorite game genre to analyze or play?

Medium · Behavioral & Alignment

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Describe a time when you had to collaborate with non-technical stakeholders, such as artists or mathematicians

Medium · Behavioral & Alignment

Describe a time when you had to collaborate with non-technical stakeholders, such as artists or mathematicians, to resolve a design conflict.

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Walk me through a complex technical project you completed. What were the main challenges, and how did you over

Medium · Behavioral & Alignment

Walk me through a complex technical project you completed. What were the main challenges, and how did you overcome them?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you handle situations where project requirements change rapidly close to a release deadline?

Medium · Behavioral & Alignment

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?