In the depicted mythos, death is not an insurmountable obstacle. There exists technology, magic, or something else that makes returning to life somewhat trivial. Regardless if this is readily available to all (protagonist usually has easy access to it).
The first video game about Cheap death was released in 1995.
Things like resurrection spells (and scrolls) as in D&D, regeneration chambers as in System Shock and BioShock, and so forth are excellent examples of this.
This is NOT synonym for unlimited lives or similar as this is purely in-mythos concept rather than gameplay.