Does Steam prevent changes to game files? There are a lot of games that benefit from tweaking or third-party patches for performance improvements or to improve compatibility with newer hardware features. Does Steam lock down game files in such a way that make INI tweaks, DLL replacers, memory injection, executable wrappers, third-party patches, or other modding methods hard or impossible?
These sorts of hacks tend to be more common and more important for older games. It does seem like some tuning is possible, but that example is for a DOSBox-based emulated game, and I just don't know how much Steam will let you do to an old Windows game.
Best Answer
Steam doesn't lock your games down, no. They can be patched, modded, tweaked, and memory-hacked just fine, so long as the original game doesn't have its own built-in DRM scheme that would interfere. And of course, anything that changes the original game files will be undone when Steam pushes down an update, so such tweaks will have to be reapplied, possibly after waiting for the tweak to be updated to be compatible with the new version of the game files.
Because Steam is both an online store and a DRM scheme, the DRM is only of the sort where your game is tied to your login and usually has to be launched through Steam itself in order to play. Locking down the files would be superfluous (though not unthinkable), and thankfully Valve has enough market sense to maintain the Steam platform's DRM at a relatively low level that mostly fades away into the background context of an online store. The only times that people report Steam's DRM being troublesome is when you don't have an always-on network connection.