Yeah, I was thinking along that line originally.

Originally, you were going to have the ability to buy health/armor/ammo, equipment, team-abilities (like vote for an air-strike, as opposed to land-strike [deploy robots]) and alllll kinds of stuff. Of course, it would have taken another millenium to get all that stuff done, so that was put aside labeled as the plans for the UT3 (then UT2007) version of Gunreal, called Ground War. I plan to pitch this as a retail game in the near future, because it would take a full team to implement all this stuff... but I think it would make for a capitally entertaining game (with a singleplayer story).
What you see on a shopping screen may look like buttons and text, but each thing has a ton of work/content associated with it that expands the game's completion time by a lot.
For example, originally, you going to be able to equip and throw ammo as a grenades, or mix ammo (like strap a lightning gun battery to a plasma gun cell), and either just throw them together for a bigger explosion, or load your plasma or lightning gun with them... but just adding 1 new type of damage per weapon adds 2x more effects that I have to make (I have to double the number of projectiles, hit effects, firing and impact sounds, and make customized meshes) 3x more code the programmers have to make (each weapon would have multiple "modes" - for example, there would be the plasma gun, then the plasma/lightning gun, and new variables for how the projectiles affect everything, and then of course they have to apply the above-mentioned stuff that *I* made), and thus add 3-4x to the overall dev time, because then you have to add the bug-fixing and fine-tuning layer on top of all that.
With a properly-sized team, it can be done. With just a couple people, it would simply take too long to attempt...
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Here's an old Photoshop concept, scrapped together as I was playing with the idea of a new vehicular gametype (until Epic stole my "War" title for a rehashed Onslaught

- Big mistake, because now if Epic ever does a *real* war gametype, what on earth are they going to call it?).
Edit: I realized they actually call it "warfare", not "war"... but still, now they're going to have to call a *real* war gametype something else, because the WAR-Mapname prefix is taken.