UPDATE: Hammer now (currently, as of this edit) works perfectly fine. However, this thread will remain as a reminder. Just a public service announcement--you may be tempted to use the Hammer bundled with Source Filmmaker to work on your TF2 maps, but DO NOT DO IT BECAUSE IT WILL RUIN EVERYTHING The VMF format that SFM uses is different from the basic SDK Hammer's. So when old Hammer starts working again and you decide to go back to old Hammer, opening your file will just make everything crash. And you will need to go back to old Hammer, because... The BSP version that SFM compiles is too high for TF2 to read. It compiles BSP version 21, and TF2 currently doesn't read higher than version 20, making your map totally unplayable and unusable for anything but, well, SFM. Now, you could just use VBCT to compile, but... You'd have to copy all the custom content you're using or change the game directory set up Which is doable, but a chore. But when you finally have everything in place, and are willing to do all the workarounds, you'll begin to notice that... While it has cool new features (multiple cordons! multiblend!) it also breaks some old ones, like most of what handles displacements Last I checked sewing and blending alpha on displacements is totally broken. Likewise, when I have used SFM's Hammer, it has felt somehow less stable. So basically... the SFM Hammer makes your map and files unusable. It's like a poison. So beautiful, so deadly. Don't use it. You're welcome!