I've voted no.4. (Just make a bug-free clone of XCOM1 with better graphics and music)
Here are my reason:-
1) The original XCom have something all other does not have... GAME BALANCE.
2) Super reaction interaction. It make turn-base playout like realtimes... many game FAIL to do that, including JA2, AND all other series of XCOM. (INCLUDING "Terror from the Deep" even they are using the same engine... the game inventory, maps and creature grew too big... hence game balance collapse)
3) Allow cheating... awkward enought... XCom allow you to do save/load in combat, and you might get different result from different action.
This some how enrich the game play experience.
Example:- You know there are alien in a room. So, you save the game.
1st try) You open the room door. Opps, reaction fire... you were dead. Reload the game.
2nd try) You blast open the room door. Opps, reaction fire again... you were dead again. Reload the game again.
3rd try) You blast open from another angle, throw in a grenade...kabooom.... you smile... cause you are happy on the out come. Don't you?
The series of events that happend above, save->load->save->load->save...is actually something very HUMAN in nature... you fail, and you try. Xcom make it better... dynamic and randomize, sometimes 30% shot do hit target, sometimes 90% do miss the target... sometime a miss hit kill an alien, sometime the alien suppose to die but after 3~4 hit, the alien still standing there... hightly unstable. Yes, hightly unstable, but somehow total UNDER control... [means that you can save and load anytime].
Try out the game yourself below....refresh your joyfull memory..
Found at google...
X-COM is still being sold. Let's not do that.