Spy robots behave much like a human Spy would: sapping Engineer buildings, backstabbing players, cloaking, disguising, and using their Knife in close quarters combat. Unlike other robots, the Spy robots spawn where the players aren't looking in close proximity to the players, as opposed to on the map's normal spawn points. Spy robots are almost always used as support, never attempting to pick up the bomb. In a few missions, though, they appear as a normal part of the wave, and will go for the bomb if it hasn't been picked up for some time or accidentally walked on the bomb, defending themselves with their Revolvers if intercepted by players.
When a Spy robot spawns, it will already be cloaked and disguised, though in most missions it will never attempt to disguise as a class the RED team does not possess. When disguised, Spies will not attack unless they're closing in on a target or the players attack first. When fleeing, Spy robots will Cloak, move a distance away, then redisguise. However, if they're +/- 45 degrees from the player's back to the player when recognized as an enemy, Spy bots will strafe within stabbing reach around the player until they get a Backstab in. If they are near death, they will stop going for the backstab and flee. Spy-bots almost always use their Knives - they will only use their Revolver if they are going for the bomb. When most spies are fleeing, they hold the Revolver, but don't actually shoot with it.
Notably, Spy bots are distinguishable from regular players due to their voices. Even while disguised, they will taunt nearby players in the robotic voice of a Spy, revealing their location to anyone paying attention. They also chuckle loudly while disguised, and when they attack, which can be heard throughout the entire map. Spy bots can also be revealed by players of the same class - human Spies cause all cloaked Spy bots in a large radius to become partially visible, as if they were taking damage.
A notification is always shown when Spy-bot(s) enters the map, and its entrance and death (only when all Spy-bots die) is announced by the Administrator.
- Spy robots while disguised use robot voices instead of human voices.
- All lines spoken by the Spy robot have a lengthy pause before the actual speech occurs. This includes the robot's death screams.
- Very rarely, when a Spy robot is killed it will spawn the ragdoll of a BLU human Spy instead of the robot counterpart.
- This is also known to happen if Spy Robots are set to use the Dead Ringer. On the Ringer's activation, a human Spy ragdoll will sometimes be spawned.
- On the occasion that a robot mysteriously appears as a giant despite being a normal enemy, Robot Spies can be seen disguised as giant versions of the players.
- If a disguised Spy-bot is viewed as a spectator, it will simply appear as a RED Spy-bot. While this may be a bug, the Spy's robot counterpart lacks the masked sub-models the original has, so it is possible that it is intentional.
The Romevision Version of the Spy.