What PC freeware/PD games are there that you'd recommend people to try out? Please, keep abandonware out.
I'll start with Dwarf Fortress, a rather massive single-player game in randomly-generated worlds. Even if the game is still in free alpha, it's got a lot more features than many commercial games. It's been a while since I last played it, but for me the main beef was the Fortress mode, in which you started building a dwarf colony, e.g., in the face of a mountain. You'd tell the dwarves where to mine, cut trees, build different workshops, grow dogs to help your hunters, grow cats to take care of pests, build irrigation systems (and be careful not to flood and drown your entire colony in the process), build traps for invaders and trading posts for more friendly visitors and much more. The other mode into which I never got is the Adventurer mode, which is more like an RPG (I never tried that out).
The graphics are, as you might've already expected, character-based, but there are some unofficial graphic updates to the game that replace the characters with icons. There are some OGG files playing on the background, but no sound effects.
The learning curve is steep, even more so now that the game added 3rd dimension and more variance to the environment. Thankfully, there are tutorials on YouTube and a Wiki dedicated to the game.


But seriously, Cave Story is really good. N is really good too