So I went and tested a bunch of games, and
wow was I wrong for modern games. Seems only old games did it, where they didn't expect huge resolution differences so they were just making a texture, and these also tended to have built-in debug menus that didn't give a full wireframe effect.
Of course these games also had to worry more about performance than modern titles but that's another rant.
Here's some modern games with wireframe hacked in, at least the ones that worked properly, 'cause of course I gotta' show it after all the testing.
Audiosurf
Not a single poly per letter... but it's obvious it's using pre-made textures, though, which skirts around the issue.
[Image: http://i.imgur.com/Q9zcIrAm.png]
[Image: http://i.imgur.com/BjV2HfYm.png]
Borderlands 2
One of the titles that plays nicely, BL1 I'd have to mess with inis to get rid of the compositing and I was too lazy. I tried some other Unreal engine-based games, but they'd need work to disable the composite shaders too and I'm 2 lay-z 4 that.
[Image: http://i.imgur.com/OiHZ6gKm.png]
[Image: http://i.imgur.com/BDl2MXum.png]
Black Mesa
I assume this method goes for other "Source" games as well, though the lack of frame clearing bothers me and is pretty evident going from poly to wireframe rendering. I wonder if there's some way I could force a frame clear or toggle the option.
[Image: http://i.imgur.com/2DfXF51m.png]
[Image: http://i.imgur.com/CfAIvL1m.png]
Fable
This was one of the titles that gave me trouble, but I managed to get shots through the Steam overlay.
[Image: http://i.imgur.com/r9Pm4Kzm.jpg]
[Image: http://i.imgur.com/u21yVsQm.jpg]
Kerbal Space Program
Wanted to get a Unity game in here too, of course.
[Image: http://i.imgur.com/j6wPnWxm.png]
[Image: http://i.imgur.com/0y9uAKAm.png]
[Image: http://i.imgur.com/ot3Mj0Lm.png]
[Image: http://i.imgur.com/GamL6sdm.png]
The Elder Scrolls: Oblivion
This game uses the old "store a snapshot of the game to pull up the menu on top of" technique so I'd have to exit and re-enter the menu after toggling modes. At least this doesn't cause the same issues as Ocarina of Time's implementation. I wonder if anybody will get this reference.
[Image: http://i.imgur.com/9PxM8LDm.jpg]
[Image: http://i.imgur.com/ckIUxPSm.jpg]
Torchlight
II wouldn't play nice even with all the settings disabled, I guess it kept a "pass-through" shader running or something, probably why II lacks a "netbook mode".
[Image: http://i.imgur.com/xSAbBQAm.png]
[Image: http://i.imgur.com/W9KA92rm.png]
I couldn't test as many games as I wanted to, some (like AC1) refuse to co-exist with other things on the screen while rendering wireframe, and others won't let me disable the shaders to get at an unprocessed rendering. Not to mention wasting half an hour waiting for Assassin's Creed 2 to simply start up only to have it install and update and reinstall Uplay 3 times just to tell me I need to make an account to play.
I also wanted to pull up a bunch of really old 3D games to show how they did it for a comparison, but the only working general-executable wireframe hack I've got is for Directx and a lot of the older games were OpenGL.