Teacher: Unreal Tournament series
Substitutes: Ratchet & Clank: Up Your Arsenal; Gears of War
Question: How do you know when your weapon selection could use an injection of creativity? Answer: When multi-page articles are devoted to dissecting the basic assault rifle's magazine capacity and range of fire. This is supposed to be a videogame, not a gun show.
To be fair, Halo's arsenal seemed pretty diverse in the beginning. Most games back then offered a ho-hum lineup of pistols, shotguns, grenades, etc... all in blacks and grays, of course. Halo had those, but added a bright neon assortment of alien technology. Weirdly shaped rifles blasted blue balls of energy, pulsated with green electricity or exploded with pink crystal needles.
Beyond the aesthetics, though, Master Chief's tools of war basically work the same. Point, shoot, repeat. The damage, speed and - yes - magazine capacity may vary, but the way you play does not. Where's the surprise? Where's the unexpected?
Surprising is a razor blade gun that can ricochet its ammo off walls, around corners and through opponents' necks. Unexpected is a towering, controllable tripod with legs that crush and lasers that burn the enemies below. But those are both in the Unreal Tournament series.
Surprising is a lava gun that spews a bendable, whip-like stream of red molten fire. Completely unexpected is a gadget that morphs other players into defenseless barnyard animals. But those are both in the kid-friendly cartoon universe of Ratchet & Clank.
Perhaps those are extreme examples, but aren't we playing games to experience the extreme? As long as it's useful, the wild and crazy stuff is always going to be more fun than the normal stuff. Heck, Gears of War's Hammer of Dawn is practically useless and it's still a blast to use.
Here's a suggestion to get Halo started - take that newly invented man cannon and stick it in the hands of the player. Bodies flying involuntary through the air can only be a plus.