A simple brush-based trigger which triggers its target once when a players enters it - never a second time.
- 1: "Monsters": If set, monsters can trigger this.
- 2: "No clients": If set, players won't be able to trigger this.
- 4: "Pushables": If set, func_pushable entities can trigger this.
- 8: "Everything else": If set, everything other than monsters, clients and pushables can trigger this. Does not exclude the above.
- 16: "Fire on enter": Not applicable on trigger_once.
- 32: "Fire on exit": If set, trigger_once will fire as soon as something that entered it left it, instead of the instant something enters it.
- Monsters are only able to trigger brush trigger entities while moving inside of them.