A SNES game, published by lucasarts and konami.

Essentially a giant robot platform game, but with more imagination than most. There is something resembling a coherent (if cliched)plot, set in the year 2102, with the United Earth Government in danger of being overrun by the evil dark axis. Their sole hope is the ace pilot Lieutenant Stone, who of course is you... The missions tie together in a believable manner, with subtle things it early cutscenes hinting at later missions. The full set of six pilotable suits are gradually phased gradually in over the course of the single player game, and the missions make good use of the ability to change suits mid-game. There is even a mission where a transport ship has to be hijacked, and Stone has to get out and storm the bridge. On foot. The contrast between almighty stomping robot, and fragile mere mortal is quite a shock... Each suit is very different, and there are often situations that can only be solved with the right suit.
The pilotable suits are:
Nitro A light, but tecnologically advanced suit, with jump-jets and a fearsome light saber
Havoc A heavier, slower suit, armed with a mace and heavy machine gun. This suit seems to be a tribute to the mecha in Assault Suits Valken/Cybernator
Prometheus An enourmous lumbering gun platform, similar in appearance to Battletech's Stone Rhino. Can't jump at all
Ballistic A light gun platform that rolls up into a ball. Preempts the Star Wars Episode One Destroyer Droid by at least six years.
Spider A spider-like suit that can climb up walls. It is equipped with a cloaking device, and can immobilise enemy suits. Similar in appearance to a Fuchikoma, but with longer legs
Drache A flying saucer like VTOL
Nicely enough, these mechs appear on the forces of both sides (Although the nitro seems to be unique to earth), and enemy soldiers will leap into nearby empty suits, and pilot them against you. The dark axis also have a few unique mechs for cannon-fodder purposes; One looks similar to Battletech's Rifleman, the other is vaguely gundam-like, with a large hand-held cannon, and a machine gun. Unfortunately they cannot be piloted.
The six suits are really well balanced for deathmatch play. No one suit is all-powerful, and even a comparatively weak suit can win with enough sneaky piloting. There is a strong rock paper scissors aspect: the huge powerful Prometheus can easily blow apart a Nitro at long range, but the Nitro's beam sabre can rip the Prometheus open in a few strikes and it can create and hide behind force-fields while firing back with impunity.
There is also a wide range of powerups, some of which take the form of a backpack which can be triggered at a later time for a quick burst of extra firepower. Again, a nice touch.
The powerups include:
Weapon powerups: 1,2,3,4 - Increase the power of your primary weapon, making the projectiles larger, more damaging, and able to pass through enemies and deformable scenery.
Bouncey weapons: B - weapon projectiles bounce off walls, allowing 'trick shots'
Homing weapons: H - weapon projectiles home in on the nearest enemy.
These powerups affect the pellets released by the shells of the Prometheus' cannon, making them especially deadly.
Full Health: + - Restores your suit to mint condition
Backpack weapons:
Mine launcher - Ejects mines from the back of your suit, which damage the next thing to stand on them. Deathmatch only
Grenade launcher - Fires bouncing grenades that do a large amount of damage
Missile launcher - Fires large missiles straight forward
Accelerator - Increases the speed and close-combat abilities of your suit
Anti-gravity - Temporarily reverses gravity

The interface and control methods are really clean and well thought out too. For every suit apart from the Drache, the d-pad does the same thing - up/down to aim, left/right to move. Every suit that can jump does so with the same button, every suit's main projectile weapon is used with the same button. There are no clunky damage meters - the suit's health is indicated by its overall colour and appearance. The suits become progressively dingier, until there are sparks coming out of them and the can no longer carry backpacks. Eventually their arm falls off and they can no longer attack. A few more hits and they will blow up. The game menus are well thought out and polished too. Every action for every suit is remappable by each player, and the menu even has a practice window to try out the new configuration.

In deathmatch mode, the loser is given the choice to shuffle the map, each player's suits or both - no hogging the game with a winning mech/map combination. The deathmatch maps all have different imaginative themes, including a metal works with lots of moving platforms and pits full of molten metal, and a pair of mountainside bunkers full of lifts and slippery slopes. An additional bonus - If you complete the game, a hidden deathmatch map appears: Play as a the game's programmers on a map styled after a basketball court!
Still working on this... My last writeup was so bad that this WIP is still beter than it...