[generated by Claude Opus 4.6, approved by Saul]

Slay the Spire 2 just came out. I wanted to play it on my HTPC (Linux Mint) with my 8BitDo SN30 Pro gamepad, like I do with StS1. The controller works perfectly in Steam Big Picture. It does not work in the game.

Here’s what I tried:

• Proton GE (GE-Proton10-32): game crashes on launch. The Godot engine (“MegaDot”) falls back from D3D12 to Vulkan, but the D3D12 swap chain code still runs and fails (swap_chain_resize ERR_CANT_CREATE). Gray screen with a black rectangle.
• Proton Experimental: wouldn’t start at all.
• Proton 10.0: game runs (D3D12 works on Intel ADL-N), but no controller input.
• Default Proton (no forced compatibility): game runs, no controller.
• Force “Enable Steam Input” per-game: no effect.
• 8BitDo X-input mode (hold X+Start to pair as Xbox controller): BlueZ can’t connect (br-connection-create-socket). The Xbox Bluetooth profile doesn’t play well with the standard Linux HID stack. Would need USB.
• Various launch options (PROTON_NO_D3D12=1, WINEDLLOVERRIDES="d3d12=d", etc.): either no effect or different crashes.

The game’s own settings screen says “configure controller remapping in Steam”, so it explicitly relies on Steam Input. The game logs are full of:

[ERROR] The input Confirm was not cached during initialization. Skipping...

for every input action (Confirm, Cancel, Up, Down, Left, Right, etc.).

Turns out: other people are reporting the same thing, on all platforms, not just Linux. Controller detection is simply broken in the initial release. It needs a patch from the developers.

Lessons:

1. When controller works in Steam but not in-game, check if it’s a known game bug before going down the Proton rabbit hole.
2. 8BitDo X-input mode (Xbox Bluetooth profile) doesn’t work with BlueZ on Linux. Stick with D-input mode or use USB.
3. Switching Proton versions rebuilds the Wine prefix each time and recompiles shader caches. It’s slow and annoying. Don’t do it casually.
4. The game runs fine on stock Proton with Intel integrated graphics (ADL-N) using D3D12/VKD3D. Proton GE actually made things worse here.