A digital cache of that size brings with it both good and bad news. On the downside, there's bound to be lots of bad games, even notoriously bad ones like the baffling 1989 fighting game Tongue of the Fatman. But on the upside, the collection also includes some legitimate classics like LucasArts' adventure game adaptation of Indiana Jones and the Last Crusade and the PC version of the Advanced Dungeons & Dragons Pool of Radiance campaign. With 2,386 games available there's far too many to briefly describe here, but you can browse the collection by visiting the Archive.
The best news, though, is that in lieu of simply archiving .exe files for each game, the Internet Archive listings feature an in-browser version of the ubiquitous DOSBox emulator. It won't be exactly the same experience you had playing these games in the late 1980s, but it's far easier than convincing games from the Reagan era to play nicely with modern computers.