Half-Life: Anti-Climax invites you to try to outmaneuver the G-Man and win the impossible battle that the sinister interdimensional bureaucrat threatened at the end of the first Half-Life.

The modification is interesting, but not particularly large. You can complete it in about 40-60 minutes, but the author tried to make the replay process more interesting by filling the maps with various hidden routes and adding two (bad and good) endings. Have a good game!