Quote: "Can this be done?"
Yes, it can be done

Assuming you're teleporting to a different level in the building and not a new game level;
Otherwise you'd need to use the level commands for jumping back and forth between game levels. If this is the method you were talking about, then it would help keep things more realistic in your game, by adding to the scripts of your key items so the engine will 'check' if the player has already picked up the Apartment Key in level 2, for example, so it won't spawn it again when the player returns to the same level. You might also want to consider giving your enemies random spawn locations, so each time you return to an ealier level, everything isn't always exactly the same.
Kravenwolf