Enter
Confirm pop-up windows
Start game from the Game preparation menu
Blitz attack button
Confirm unit transfer (slider)

Esc
Close pop-up windows
Open/close in-game menu
Cancel unit transfer (slider)
Close all cards in main menu
Open exit card in main menu if all cards were closed

Space
Proceed to next game phase
Skip AI turn

F1 (H button on Mac)
Open in-game help