The Hologuise is a type of gadget in A Crack in Time. It enables the user to disguise themselves as someone else using a hologram. In A Crack in Time, Ratchet disguises himself as Dr. Nefarious to infiltrate the Nefarious Space Station.
The Holo-Guise is used by Ratchet to infiltrate the Nefarious Space Station and take over Hypernova Defense Laser. The Nefarious disguise is created by Clank, using a gigamorphic holo-ray installed in Clank to take a scan of Dr. Nefarious and disguise Ratchet. The holographic disguise ended up shorter than Dr. Nefarious due to Qwark forgetting to tune the autoscaler, causing Ratchet's apparent height to stay the same. It allows Ratchet to sneak by Nefarious' minions, but after completing the mission, Nefarious is alerted to Ratchet's presence and it becomes ineffective.
Additionally, Alister Azimuth suspects that Ratchet is using a Hologuise, before calming down.
The Hologuise when activated disguises Ratchet as a specific enemy, allowing him to go traverse undetected. It is often used to unlock doors that will not allow Ratchet through otherwise, either by waving at a guard behind the door or completing a short minigame while disguised. Ratchet's movement is restricted with this disguise active, as he often moves more slowly, and often cannot jump while using it. Pressing the fire button with a disguise on will wave at enemies. He cannot use weapons or gadgets.