Nightdive has created a fantastic package here. The game, reproduced in their Kex Engine, runs perfectly. And they've added a few visual tweaks to improve the experience. You get the base game, the original mission packs, and the short expansion released to mark Quake's 20th anniversary. On top of that, MachineGames has made a new expansion that's more of a mini-campaign that brings Quake into the modern era with a delightful set of new levels.