Thief 2 improved upon the original in nearly every way. The game features better lighting effects, more cool gadgets for Garrett to use, and a wider variety of scenarios, environments and challenges in each level. The story takes some surprising turns and fleshes out even more of the universe and development for the protagonist, something essential for a sequel to do. Given how expertly this game was made, it's a real shame it would essentially be Looking Glass' last release before their bankruptcy. About the only real downsides I can think of is that some of the levels can be surprisingly difficult to the unprepared, and perhaps due to community feedback there's one level with a forced "ghosting" requirement, and thus I highly recommend liberal use of the quicksave feature.
A follow-up game after the success of Maniac Mansion, Zak McKracken and the Alien Mindbenders takes place in San Francisco in 1997, with the protagonist McKracken, a burnt-out tabloid journalist, having a very interesting dream that turns out to be a secret psychic message with instructions on how to stop a planned takeover of the world from malevolent alien forces. Said aliens are using certain high-frequency sound waves via a "Mindbending" device, to render humans too stupid to fight back. This adventure takes you all over the world and even to Mars, with some crazy puzzles and plenty of offbeat humor to keep the game engaging. I will warn players that this was made *before* LucasArts had a "no dying, no unwinnable states" policy so saving the game often and remaining careful is required (luckily, this edition uses ScummVM which includes far more robust save game options than the in-game save system). The GoG release is the 1990 FM Towns version with full 256-color graphics and CD-quality music, far better than the original 1988 PC port that featured 16-color graphics and PC speaker sound only. I actually beat that old version around 10 years ago and didn't mind those limitations too much, but this more polished version has me much more excited to replay it! A must for classic adventure game fans.