Use button
From OHRRPGCE-Wiki
The Use Button in GAME.EXE is the button that players press to talk to NPC's, open treasure chests, select menu items, and choose target enemies in battle.
The use button is not actually a single button, it can be any one of the following:
- Space Bar
- Enter
- CTRL (both right and left)
- The first joystick button you press on the title screen