1. Place a group of units (call them GROUP1 for exmpl.).
2. Place the module "Show / Hide".
3. Set the module to hide and for groups of synchronized objects.
4. Synchronize the module with the group1 team leader.
5. Place a player from Op. side in front of group1.
6. Press Preview.
7. Player don't see enemy units but CAN HEAR enemy communications.