Characters in a Space can spar with each other. Combat is friendly by design: a knockout never has any lasting effect.
Attacking
Stand next to another character and press Space — or tap the sword button on the on-screen pad — to swing your weapon. The swing connects with the character on the tile you are facing, or with whoever is standing beside you.
Taking hits and health
A landed hit staggers the target and deals damage. Hurt characters show a slim health bar under their name; it disappears once they are back at full health.
Knockouts
At zero HP a character is knocked down and stays on the ground for a few seconds — they cannot move, attack or be attacked while down. They then get back up on their own with full health, ready for the next round.