Underdeep Steam Deck support comes down to two things: the game ships with Linux support, which is the platform SteamOS runs on, and its interface is entirely pointer-driven, which the Deck's touchscreen handles well. No Steam Deck compatibility rating or statement has been published.
Underdeep Steam Deck support: Linux requirements and no rating
The store page lists Linux support and no Deck compatibility rating or statement has been published. The Linux requirements are:
| Requirement | Minimum | Recommended |
|---|---|---|
| OS | Ubuntu 22.04 LTS (64-bit) | Ubuntu 24.04 LTS (64-bit) |
| CPU | Intel Core i3 or equivalent | Intel Core i5 |
| Memory | 4 GB RAM | 4 GB RAM |
| Storage | 2 GB | 2 GB |
| Network | Broadband internet connection | Broadband internet connection |
macOS is not supported at all.
The game is entirely pointer-driven
The game is built in Unity and is entirely click- or touch-driven: the map is clicked or swiped, the menus are mouse-driven, and there are no controller buttons to map. That makes the Deck's touchscreen the natural way to play it, and the practical test is the demo, since the engine is Unity and the interface needs only a pointer.
The movement itself is the part that changes on a handheld, and the details are in the movement timer guide.
Two things to keep in mind on a handheld
- The game needs an internet connection, so it will not start in flight mode.
- The 3-2-1 movement delay plus the word-by-word text makes it a slower session on a small screen than it is on a monitor.
Where saves live
Linux save data lives at ~/.config/unity3d/Hakony/UNDERDEEP. The same migrate_r and migrate_r1 recovery procedure applies there if the game will not launch, and the steps are in the known problems guide.