Tron 2.0. I watched Tron recently, which reminded me that it would be cool to replay Tron 2.0. I know a lot of people like the Tron Legacy movie, but IMO this is still the real sequel. It just feels more like the original movie to me and the way it expands on the movie's setting feels truer to me than the movie sequel. I also just like the characters and overall story, involving corporate espionage and computer viruses, more.
This was made back when Monolith was still a very good developer - although it would be fantastic for GOG to get the No One Lives Forever games, this came out right around the same time and it's very similar in a lot of ways. It's just doing Tron on the Lithtech engine is all. You get a variety of weapons you can use, but aside from one or two spots where the LOL (sniper rifle) comes in handy, I just stick to the disc the whole way through. Blocking enemy throws and then head-shotting them with the disc never gets old. Unfortunately, I don't think the light cycles portions work especially well in this. Their inclusion feels obligatory and not much else.
Half-Life. I also had an itch to replay Half-Life for the first time in like 15 years. It's still a very good game, although I find it a bit uneven overall. The early portions are fantastic, with everything building smoothly and then keeping a great sense of tension and exploration in the aftermath of the accident, but then around the points where you start riding the rails and going underground, I found my attention lessening and the game never really gets back to that early feeling, starting to feel grindy as it goes along, and then of course you get to Xen with its loose platforming and the game ends on a squishy note. I had this initial idea that I might go ahead and replay the expansions and then continue into Half-Life 2, but around the point where you're riding the little handcar around the tunnels, contantly starting and then stopping to open gates and crap, I realized that Half-Life 2 expands on that concept in a really bad way with its vehicle sections and I was cured of any desire to replay it.
Nixy the Glade Sprite. One of those recent homebrew games made for the ZX Spectrum. You control a fairy named Nixy, whose apparently really hot based on the loading screen but is just a humble cartoon character in-game, and you have to run and jump around various screens collecting stuff to save the forest. First you have to have find the Gaia Stone and take it to the Moon Pool, then you're directed to collect 10 Moon Blossoms and take those to the pool, and then the game makes you take the Gaia Stone back to where you found it. Once you get the hang of the gameplay you can comfortably finish it in an afternoon, which is what I did.
I'm always very impressed by how adept modern programmers are at squeezing more graphics and sounds out of these old machines, each one having its own particular vibe, which is refreshing in this age where even consoles are basically just mini gaming PCs. The Spectrum in particular has this knack for moody exploration games like this one, with its deep solid colors on top of pure black backgrounds.