Software used for developing, and editing, games.
Often these titles will refer to a series of programs, rather than a particular one.
Designed for making no game type in particular, though they can suit some ideas more than others.
Software designed for making games in particular genres. Though they can often be used, through force, to create other things.
Level editors, and such, included within games, and those by other parties designed for specific games.
For software for use on hardware that is not a PC or Mac. Many of these also have PC—often DOS—versions, and will be listed twice.
Programs for the creation of game assets, with an emphasis on freeware.