Tier0.dll is part of the PC game engine. Basically without it, there are several games that might not be able to launch. This is particularly so if you are using the Steam distribution channel. This is because without Tier0.dll, the MDL decompiler cannot run. For any avid gamer having issues with their Tier0.dll, the solution is quite simple. Simply download another version of the file and install it. And voila! It should be working. Getting this dll file should not be a hassle as well. Look no further, simply click here and you should get the Tier0.dll download.