Thank you so much! And thank you even more for the gamepad report — it was a real bug, not your controller. The pad input was only ever registering button presses, never releases, so the first time you touched the D-pad that direction stayed stuck down forever and the ship just pinned itself against the edge. It never showed up in testing because on keyboard the key-up event was hiding it.
It's fixed and already live (v0.22.2) — a refresh should get you the new build. Gamepad now works properly: stick or D-pad to move, A/X to fire, B/Y for bomb, LB/RB to switch weapon, Start to begin, Select to pause. You can even mix pad and keyboard now.
If it still misbehaves with your pad, tell me which one it is and I'll take a look — thanks again for catching this.