Epic's free third-person puzzle platformer sample, rebuilt from the ground up for Unreal Engine 5.6. It includes a playable platforming character, physics-based puzzle mechanics, procedural level-building tools, modular objective systems and UV-less materials, with in-game developer commentary explaining the design. Runs from mobile to high-end PC with touch, gamepad and keyboard input. Delivered as an Unreal project through Fab.
At a glance
Licence
custom
Commercial use
commercial OK
Credit
Not required
Status
needs-review: Useful, but a real question is open. Verify before you ship.
Contents: playable robot character, physics puzzles, procedural environment tools, objective and progression systems, commented Blueprints and materials
UE versions: the Fab listing's "Unreal Engine versions" field read 5.0 – 5.8 on 2026-10-13. The description says the project "has been fully rebuilt from the ground up for Unreal Engine 5.6" and that the older sample needs an engine version before 5.6, so 5.0 to 5.5 get the original project and 5.6 onward get the rebuild
Licence: Fab Standard License, free on both tiers. The current description has no "UE-Only Content" line, so engine_lock is omitted. Open question: Epic marks Lyra and Cropout UE-only but not this listing; confirm on the listing before exporting the robot or props to another engine. Kept at needs-review for that reason
Redistribution: this is Epic content and may not be redistributed in source form or committed to a public repository. Epic's content licence says you "may not Distribute Licensed Content in source format to third parties except to employees, affiliates, and contractors who are utilizing the Licensed Content in good faith to develop a Project on your behalf"
Gotchas: the pre-5.6 and 5.6+ versions are different projects, so tutorials written for the original Stack O Bot will not match the rebuild
Evidence
Live Fab listing (2026-10-13): "License terms" "Standard License"; both Personal and Professional tiers priced at 0 USD; "Unreal Engine versions" "5.0 – 5.8"
Same listing description (2026-10-13): "Stack O Bot has been fully rebuilt from the ground up for Unreal Engine 5.6."; "If you want to access the older Stack O Bot sample, you will need to download the project for engine versions preceding 5.6."; no "UE-Only Content" line present
Live Fab EULA Standard License summary (2026-10-13): "Use the assets commercially or privately"; "You are not required to give credit to the publisher you acquired the Fab asset from"; "You may not: Resell or redistribute the asset for free on a standalone basis"
Live Unreal Engine content licence (2026-10-13): "you may not Distribute Licensed Content in source format to third parties except to employees, affiliates, and contractors who are utilizing the Licensed Content in good faith to develop a Project on your behalf"