In an old post I talked about a small idea for console shooters: basically instead of the current system of reloading, where you can drop an almost-full magazine without losing any ammunition, you would tap the reload button to quickly drop the magazine and lose the ammunition (which could be picked up again manually later) and load a fresh one, or hold the button to remove the magazine and stow it before loading the new one - this would be much slower but you would keep the ammo. The idea is for use in games where ammo isn't plentiful and resource management is a bigger deal, obviously.
Well, I just finished Army of Two: Devil's Cartel, and one thing I really liked about that game was the weapon selection system. I had an idea for a slight tweak to the formula. The basic idea is that the player can carry a number of main weapons and a handgun. It would probably be two main weapons which would typically be long-guns that can be slung behind the player's back, while the handgun fits in a holster; that seems reasonably possible in real life (not necessarily practical, but possible). In a similar way to Rage, a single tap would quickly switch to the handgun and back while holding the button would open a weapon-wheel.
The twist is that when performing this quick-draw the player doesn't put away his primary weapon, instead he keeps carrying it in his off-hand while shooting the handgun one-handed. Because he doesn't need to hang up the primary weapon the draw can be extremely fast, but because he's firing the handgun one-handed he won't have as much control, meaning accuracy and rate-of-fire suffers. Of course he wouldn't be able to reload the pistol with both hands full, so hitting the reload button would holster the pistol and reload the primary. unless the character has some kind of rig that holds magazine up so that the handgun can be brought down onto them to reload, like Lara Croft sometimes uses - that could be an upgrade item you pick up later. When selecting the pistol using the weapon wheel, he holds in in both hands so he can fire and reload it normally of course.
If the primary weapon could reasonably be used one-handed - another pistol or perhaps even a small submachine gun - then quick-drawing the pistol would allow the user to dual-wield the two weapons. I think it would be reasonable to be able to reload while doing so (the animation could involve tucking one pistol under the arm while reloading the other, for example).
This probably all sounds quite complicated on paper, but I don't think it would be that complicated in use, and it would complement my older reloading idea. So why bother with all these complicated micro-management systems? Well, because they add depth to the basic shooter gameplay. They force you to make rapid tactical decisions on the fly: do you reload and risk getting shot or killed before you can return fire, or quick-draw a pistol to fight your way out of trouble but delay getting your primary weapon back up? Hopefully it would make the right game more engaging. At any rate I expect it would appeal to some gamers; unfortunately those are probably PC gamers.