First of all: Bubbles, how the fuck do you run out of ammo on Deux Ex at the end stages of the game? I had tons of it and I was a rifle totting gimp. Granted, I *may* have ended up crouching and headshotting all the MJ12 commandos and MIB/WIB from a distance when I wasn't sporting a plasma cannon or gep, but even so, lots of ammo on me, and lots dotted around the base in crates/behind doors.
Now, I actually like the modular system for ammo, the problem with it lies with design. You need enough ammo types that you can use various weapons and not be completely out, but you also need to limit it to a degree so you can't run around with your plasma cannon of doom +5 and gibbing everyone on sight in the later stages.
This is where I love Oni (told you it works great in this), the modular system may only consist of 2 ammo types, but you obtained ammo
clips, and you could only hold 6 clips of each iirc. The fun part is that the guns on reloading used up an entire clip, but that clip could be in the region of 2 shots to 50 rounds
depending on the gun.
Tactical trade off, do you pick a "medium" gun so you can use it lots, or a more damaging weapon but use it less as you eat through your clips quickly?
Sounds a bit odd, but it worked a treat, possibly because you also had the option of going kung-fu on everyone's ass as well, so you didn't actually need to use a gun to kill someone.
It's where DX2 fell down, as there was only one ammo type, if you needed to use something big you'd eat up all your ammo, then you had pretty much nothing left for the peashooters.
Fallout 3 is the other extreme, as it's added even more ammo types (eg, the Gatling Laser doesn't use Micro Fusion Cells like in previous games, it's got it's own Electron packs).
On that game I've got a silly excessive amount of ammo for some guns, but that's also down to whoever designed the "condition" system being a pigeon huffing cock monster, as I'd be goddamn suprised if many guns completely die after only a few of hundred rounds, especially as they're pretty much all ex-military, I'd accept it for the rarer experimental ones (eg, Plasma rifles etc) but not for common ones like shotguns and assault rifles.
I'll also point out revolvers pretty much never fail, same for the sawn off shotty, as they're extremely basic weapons, they should in essence, be the back up guns if your others break. Even the hunting rifle falls under that category, it's not a complex gun (or at least, they could have introduced a single shot one as a longer range backup)
It also means I can't really use the fun weapons as there's not a lot to repair them with, again, flawed. A simple fix would be to treble all the gun health in that game, and double the armour health as well. It would also save having to haul around 3 or 4 extra ones for spare parts, stupidly unrealistic that is.
And having too many ammo types (or not enough guns for one ammo types) leads to not using weapons due to availability of other ammo for other guns. Fear was bad for that, as every gun had it's own ammo, ran out and that was it with that gun, sometimes for quite a while.
A nice balance needs to be struck somewhere in the middle, most games handle it well (you do need some sort of unlimited ammo weapon, but this can simply be the butt of the weapon you've got, or your fists/feet, or even a knife or baton), and I hope DX3 does that.
TL:DR:
Modular with a number of different types: Very good.
Modular with one ammo type: Doubleplus bad.
Lots of ammo types for guns: Good
Lots of ammo types for lots of guns: Not so good.
F3: Condition system is flawed
DX2: Single ammo type was a game killer
Oni: Awesome, buy it cheap, it's good fun
Deus Ex 3 inspired by BioShock
