Except in cases like a bomb going off, where a timer would seem quite natural. But in other cases it might be better to show in in the environment, visually, and audibly, the escalation of danger as time goes on. When the player eventually fails the mission they shouldn’t lose because...
have an enemy that’s mostly a solid color, with a couple lights on it, the lights die if the player gets too close or the timer runs out and then as an oh-shit warning, a circle of light starts rapidly expanding from the center-of-mass or the bomb sector of the bot, followed sh...