Interformic Games offers a free miniatures game called Turn or Burn. The authors write:
Turn or Burn is a fast-paced game of space fighter combat for 2 to 8 players. To start a game, you design your fighter from a deck of system cards. Each turn you play a system or maneuver card facedown to plot the action your fighter will take. The game uses vector movement, so you must plan ahead! When everyone has plotted, all players reveal their actions simultaneously. Fighters move, guns fire, stuff explodes, and it’s on to the next turn.
There also are several modules for more detail.