Roblox Interview Questions — Page 12

Roblox·Software Engineer·Technical Phone Screen

Jun 2026

Roblox SWE interview with a simulation-style coding problem that had more moving parts than I expected. The candy crush board question sounds like a fun leetcode problem until you're actually implementing it under pressure.

Given a 2D grid representing a candy board, implement a function that repeatedly crushes groups of 3 or more same-type candies (horizontally or vertically), applies gravity so remaining candies fall down, and returns the final stable board.

“Three distinct phases and you have to get all of them right.”

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Roblox·Data Scientist·Technical Phone Screen

Jun 2026

Roblox data scientist interview with a coding/technical problem that looked like a stats exercise but turned into a full ML pipeline question. Pretty involved for a single prompt.

You're given a labeled binary classification dataset with numeric features. Walk through how you'd z-score normalize the features, fit a logistic regression, then rank and return the top 3 features by coefficient magnitude. Also explain any modeling choices you'd need to make explicit, like how you handle regularization, the intercept, or zero-variance columns.

“More involved than I expected.”

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Roblox·Product Manager·Onsite - Product Sense / Strategy

Jun 2026

Interviewed for a PM role at Roblox and got a product strategy question about protecting digital assets on the platform. Pretty niche angle I hadn't prepped for.

How would you approach protecting Roblox's intellectual property, including things like 3D objects, character skins, and accessories?

“Wasn't sure if they wanted a legal answer, a technical one, or a product one.”

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Roblox·Data Scientist·Technical Phone Screen

Jun 2026

Roblox data scientist interview threw a pretty dense SQL question at me that combined fraud logic, age calculations, and chargeback lookups all in one query. No window functions allowed, which was the annoying constraint. Felt okay about the structure but definitely second-guessed some of the edge case handling afterward.

Using only CASE WHEN and JOINs (no window functions), write a single SQL query that returns, for each user with at least one payment in the last 7 days, their user_id, total payment count in that window, count of suspect payments in that window, and a Y/N flag for whether they have any chargeback on payments from the last 60 days. A payment is suspect if the user was under 18 at the time of payment, the user's country doesn't match the payment's ip_country, or the payment happened within 24 hours of account creation and exceeded $10. The chargeback flag covers any chargeback timestamped on or before today linked to payments in the 60-day window.

“This one took me a minute to even parse.”

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Roblox·Machine Learning Engineer·Technical Phone Screen

Jun 2026

Roblox ML engineer interview had a system design coding problem that felt more backend-y than I expected for the role. The question was clean but the follow-up constraints are where things got interesting.

Design an in-memory hit counter that tracks how many requests occurred in the last 5 minutes. Implement two methods: one to record a hit at a given timestamp, and one to return the count of hits in the past 300 seconds relative to a given timestamp. Timestamps are strictly increasing but multiple hits can share the same timestamp. Optimize so that queries don't scale with total hits ever recorded.

“My first instinct was a queue and I said so out loud, which was fine for the basic case.”

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Roblox·Software Engineer·Technical Phone Screen

Jun 2026

Took a Roblox technical interview with two coding problems and came away unsure whether thorough testing can make up for missing an edge case on the second one.

Two technical coding problems were given during the interview. The second problem had at least one edge case that was missed during the solution.

“Got through both problems but fumbled an edge case on the second one.”

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Roblox·Product Manager·Onsite - Product Sense / Strategy

Jun 2026

Interviewed for a PM role at Roblox and got a product safety question about private messaging. Pretty focused on trust and safety thinking, which makes sense given the platform's audience.

How would you design and prioritize safety features for a private messaging system between players on a platform like Roblox?

“This one has layers you don't immediately see.”

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Roblox·Software Engineer·Technical Phone Screen

Jun 2026

Roblox software engineer interview with a pretty meaty coding problem involving prefix matching and custom sorting. No behavioral fluff, just straight into the algorithm.

You're given a list of query strings with associated timestamps, plus a list of prefix strings. For each prefix, find all distinct queries that start with it, then return them sorted by descending frequency, breaking ties by the earliest timestamp that query appeared.

“The sorting logic is straightforward enough but the scale is the whole point.”

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Roblox·Software Engineer·Onsite - System Design / Architecture

Jun 2026

Two-part system design interview at Roblox for a software engineering role. Both parts were dense and covered a lot of ground fast. Left feeling like I had scratched the surface on most topics rather than going deep on any of them.

Design a resource loader that supports multiple resource types such as images, configs, and ML models. Cover the public API surface, how new types get plugged in, async and concurrent loading, prioritization, batching, caching at both memory and disk layers, eviction, deduplication, retries and timeouts, dependency resolution, streaming or partial loads, failure isolation, thread safety, and observability.
Design a ROS-style publish/subscribe messaging system. Address topic definitions, message schema and serialization, service discovery, QoS and reliability modes, message ordering, replay and durability, backpressure and flow control, slow or disconnected subscribers, partitioning and scaling across nodes, real-time and latency constraints, clock sync, fault tolerance, and security. Also compare brokered vs brokerless and federated topologies and justify your design choice.

“This was a beast of a question.”

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Roblox·Machine Learning Engineer·Onsite - System Design / Architecture

Jun 2026

ML system design round at Roblox for an MLE role. The question was a full end-to-end design problem around game genre classification, which sounds contained until you realize how many rabbit holes it opens up. Left feeling like I covered maybe 60% of what they were probably looking for.

Design a complete ML system from scratch that classifies games into genres. Walk through problem framing, data sourcing, modeling approach, training, evaluation, serving, and how the system evolves over time.
How would you handle class imbalance for niche genres, and what evaluation metrics make sense here?
How do you structure the feedback loop once the system is live? Specifically, how do editorial review and user-applied tags feed back into the model.
Walk me through the iteration roadmap. Where do you start and what does the path to a full multimodal system look like?

“This is the kind of question where you can spend 20 minutes just on taxonomy and never get to modeling.”

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