Grab some toy soldiers (Games Workshop, BattleTech, Lego, whatever), a handful of six-sided dice, and clear off a 20x20 cm space on your desk.
Arrange the soldiers within the play area. Place 3d6 by each soldier.
On its turn, a soldier may move or attack. Never both.
To attack, remove 1d6 from a soldier's dice pool and roll it. Ranged attacks hit on 4 or greater. Melee attacks hit on 3 or greater.
When a soldier takes damage, remove 1 die from its dice pool.
When a soldier's dice pool is reduced by damage to 0 or less, tip it on its side to signify that it is dead.
The last soldier or soldiers left standing when there are no dice in the play area wins.
These rules are Creative Commons CC BY-SA 4.0, but you can also download them from Itch.io