Lookout used in a sentence

Lookout in a sentence as a noun

Was there some additional circumstance involved here, some other pitfall people should be on the lookout for?

Doom was not some simple little game, it introduced the concept of circle strafing and multi-level enemies in FPS.>The jittery feeling of older games, where every shot counts and you always have to be on the lookout for your opponentHa, really?