As usual for the Build Engine era of games, Blood is a masterpiece that deserves a replay through an updated port, and Kex Engine does a fine job of running the game on modern systems.
Doom 3 remains a very good vanilla experience, but what sets this apart from other games from that era is the open source code, the Doom community is known for their ports and all kinds of mods, and here Doom 3 is no exception. Grab dhewm3, Phobos, tweak your graphics a bit and have another round at this 2004 classic.
Dark Forces remains as good as when it was released. Using the Force Engine port along GOG's DF version makes for quite the enjoyable experience -- higher resolutions, true 3D view, quick options menu, quick saves and a bit of eye candy. The only downside in DF is that it ends.
Q4 is a very decent corridor shooter, but feels a tad more dated than Doom 3 thanks to not having as many mods or source ports. It's a solid IdTech 4 experience, but imo GOG should try to get the full source code open so the community could do more than it currently can.
