You get one life and no saves. However, the deflibrilator does not count as a death and you can play this on easy mode. Very similar to the Iron man mode on Metro Exodus. One tip, be very very careful at the last level when you get the predator car. Whilst driving through, it will only take two hits by barrels or by the enemy predator cars before you are dead. I got half way through not realising how much damage you can take and actually bottled it and did the rest of the tunnels on foot...which is dead easy on easy mode. Be careful as you don't want to get all this way to die in a car! I raced through this in a matter of a few hours and just went for the shatter, vortex, slam and rocket launcher Ark locations before doing anything and then just stuck to the main missions. On easy, this game and this mode is a breeze.