The M.U.S.C.L.E. Mega Match Game was a board game that you could play with your favorite M.U.S.C.L.E.s. Here is a description of the game according to the back of the box:

Announcing the match of the millenium! Weird, wild
M.U.S.C.L.E. things are trying to muscle in on your
territory! Now it's time to choose a leader and challenge
the ugly invaders to a championship showdown in
the special M.U.S.C.L.E. arena.

Object of the Game:
This is a battle to the last man-or THING!
Be the last player to have one of your M.U.S.C.L.E.
brawlers still standing and you win the game!

This Game Includes:
1 Special M.U.S.C.L.E. Arena
(built into box bottom)
10 M.U.S.C.L.E. Creatures (including
Terri-Bull and Muscleman)
1 Spinner
1 Sheet of Press-on Labels

The Mega Match game box had a few interesting features. First, at the top-right of the front of the box, you can see many of your favorite MUSCLEs cheering the match (including an outline of Tortle to the left). Also, the box front featured a shot of the Muscleman and Terri-Bull supposedly included with the game. The Terri-Bull, you'll see, is actually not the sculpt included.

The 10 M.U.S.C.L.E.s included in the game were made up of five good guys and five bad guys, with Muscleman and Terri-Bull as the leaders (of course). The bad guys were the common M.U.S.C.L.E. green, while the good guys were a light-purple color that was only available with the game. The figures were the same for all games, so there are only five light-purple M.U.S.C.L.E.s. The green Terribull was exclusive to the game as well, even though the other green figures were not, as they have been discovered in 4-packs. See the pic below.

As you can see from Soupie's MUSCLE Colors Image Archive, the grape figures all come from Kinnikuman Part 8, tree 1, while the green figures mostly come from Part 15, tree 1. (For an explanation of MUSCLE trees, click here.) The only enigma is the green Terri-Bull.

You can view the game rules online by clicking here. The game actually sounds like it's pretty fun! Check out other pics of the board game below. In the loose shots, some of the stickers that came with the game are applied to the arena.