Manual/Singleplayer/Time Units/v2.4

Combat in UFO:AI is executed in rounds. During each round all units on the map controlled by the active player can perform actions. Time Units (TUs) determine how many actions a character can perform in any given round.

The number of TUs allocated to each character is depending on his speed skill. They are indicated as the blue bar in your soldiers status window. At the start of each round the TU pool for each character model is reseted. Every action of the character will spend these TUs until his TU pool is depleted and the character can’t perform any actions until the next round.

It is possible to reserve TU. This can be useful to ensure that on a later point in the same round your character still has enough TUs left to shoot his weapon. Or TUs can be saved for Reaction Fire which basically enables your character to spend these saved TUs during the enemies round.

So remember: always watch your TUs, because a soldier who’s unable to move quickly becomes a dead soldier (never going to move ever again).