ReactOS on Twitter: "Valve Hammer Editor 3.4/3.5 now works on #ReactOS, even loads maps and textures, thanks to recent patch by I_Kill_Bugs! You see the results of his contribution, so don't hesitate
Valve Hammer Editor
Hammer like mapping in Blender tutorial - Blenderheads - Mod DB
Hammer Block Tool:de - Valve Developer Community
source engine - Can't Use Hammer Editor Grid or 3d Camera - Game Development Stack Exchange
Quick Tip #07 CS:GO Source: Free Rotate or Snap Rotate 15 Degrees to Stay on Grid Hammer Source - YouTube