In Release 6.0 Build 126.2 · Anuken/Mindustry · GitHub :
The key you just pressed is not recognized by SDL. To help get this fixed, please report this to the SDL forums/mailing list https://discourse.libsdl.org/ X11 KeyCode 129 (121), X11 KeySym 0xFFAE (KP_Decimal).
- it’s a dot key on keypad