My ideal shooter would be Halo: Reach alpha zombies in a map the size of the map in dayz (225km2) with ~20,000+ players

My ideal shooter is something like Axelay, Gradius, Sin & Punishment
imo FP games should have adventure elements and couldnt be labeled as shooters, ala Metroid prime

Star Wars Battlefront 3 or Timesplitters 4. Whilst I never really liked the campaign of the Timesplitters games I absolutely adored the multiplayer portion, same with Battlefront, two truely great game series that desperately deserve continuations there. Whilst I am very much looking forward to Halo 4 I have always envisioned properly massive multiplayer battles in a Halo game that I know Halo 4 wont deliver i.e. 128 players minimum, on huge maps that require smart use of vehicles for transport and support as well as co-ordinated infantry maneuver.

I would love games to offer amazingly precise character and item customization down to the length of you characters fingers for instance or even completely inventing your own kind of weapons or armour rather than selecting pre-sets.

It seems you want a persistent world MMOFPS.
I rather have a great single player experience like Half-life 2, Stalker or Dead space.
Carefully crafted environments and story is more appealing to me then randomized maps. The more logical the maps are the better the immersion is for me. Max Payne 3 failed horribly with it's silly connecting rooms layout.

MAG is the perfect shooter for me. Multiple objectives on the map. Ability to call tactical strikes. 8 man squads. Not too much health but not too little. Perfect game imo. Absolutely no lag(can't say the same for Battlefield -_-). Just buy MAG, it is amazing.

I want everything great about this game (but not exactly the same controls since it doesn't lend itself to multiplayer)...

...paired with the upgrade system and open combat scenarios of this game...

...featuring many role-playing elements including crafting, along with building and resource gathering comparable to this game...

...coupled with local and onine co-op, and persistent competitive online multiplayer (entirely team-based, because I never play deathmatch anyway).

So basically, combine ALL my favorite things! XD

@SvennoJ

You hit the nail on the head, a persistent MMOFPS is exactly what I want from a FPS. As far as a single player experience goes, I would much rather carefully and meticulously perfected level design such as in the case of Half-Life. The thing is though, this doesn't work in multiplayer. Case in point, Call of Duty. Veterans simply memorize the maps to the point at which they know when and where to spam their grenades at the beginning as to blindly kill new players. Everything is routine with such maps and I can only see them working with some form of randomization.

@F0X

Now there's a fantastic contribution. Metroid Prime was one of the best FPS games of all time and the additions from Crysis 2 and Minecraft would certainly make for a compelling experience that I would purchase. Anybody else with an idea for the "ideal" shooter?

I am so much into Battlefield 3 that I hardly want to play anything else.
If Battlefield series could offer in their Campaign mode what they offer in their multiplayer, and by that I mean a non linear, multi layered, huge scoped, massive experience, then I would be totally satisfied.

Bioshock was the ideal shooter.