Low Eco

Ghost glitch, previously known as Nuka glitch, is when Jak is able to continue walking while the game thinks he is dead. Upon triggering the glitch, Jak will still have 1 health remaining but will be unable to collect power cells, precursor orbs, scout flies, or eco. If Jak already has blue eco when the glitch is triggered, and causes other collectables to be attracted to him using it, they will trail Jak around but not be collected. Other side effects include enemies not targeting Jak and Jak being unable to interact with NPCs and environmental assets such as the Gondola and warp gates. Methods of removing ghost glitch include: bonking, dying, loading a save file, and resetting the console. This glitch shares many similarities with the invulnerability glitch in later games of the series.

There are two known methods to trigger ghost glitch:

• by Jak dying and collecting a power cell on the same frame. The game will believe that Jak has died, but the death sequence is interrupted by playing the power cell cutscene. Once the power cell cutscene ends, ghost glitch will be active.
• by performing a lava walk while Jak has only 1 health remaining.

Ghost glitch was once used in the Low Eco category to complete the Mountain Pass race on foot, but it is no longer used in the current route. It is also the only known way to complete the precursor blockers in Snowy Mountain without collecting precursor orbs. Cloning scout fly power cells with the dupe state can be used to activate ghost glitch without making the power cell unobtainable.

Technical

When Jak dies on solid ground, the game changes Jak's state to one that triggers his death animation and makes him unable to interact with collectables, NPCs, and environmental assets. Interrupting the death animation by collecting a power cell on the same frame that Jak dies will bypass the death animation but retain the death state. This allows Jak to walk around while death state is active.

Discovery

Ghost glitch was first discovered accidentally by Nuka, hence the old name Nuka glitch, and he shared some (no longer existing) footage of green eco trailing Jak and being unable to collect items. Because he wasn't sure how he triggered the glitch and wasn't recording until it happened, it wasn't replicated for several years after its accidental discovery.

Other Notes

The name was changed from Nuka glitch to Ghost glitch to more accurately represent what was occurring during the glitch. The Jak speedrunning community strongly advises against discoveries being named after the people who discovered them.