Quake II Mission Pack: The Reckoning (PC Games, 1998)

The first official mission pack for Quake II is a cohesive, if conservative, extension of the original, offering more weapons and opponents along with plenty of solid single-player and deathmatch levels. The question you need to ask yourself is whether you enjoy Quake II enough to merit playing it again, because The Reckoning is a supplement rather than an improvement. You're still just one marine up against the evil biomechanical Strogg, and though you'll take up a few new guns and see a few new sights, The Reckoning remains thematically identical to the original Quake II campaign.