Co-op/Compet. Mechanic.

I'm sure this has been done before, but I need a few brainstorming ideas on how to implement this mechanic.

There are X "Towers" that are to be built. Each "tower" has a height that must be reached for all players to gain points. (These would change with each playing). Each player has their own secret heights they want each tower to reach. These will not all, or perhaps not any, be the same height as required by the game.

Players gain points at the end of the game for each tower that matches what the game wanted. They then gain bonus points for towers that matched their secret towers.

Players lose points when the games tower isn't correct. They also lose when their secret towers don't match.

Each player then compares his secret tower to what the game wanted. The greater the diviation, the more points he losses for each "height" the tower is away from what the game wanted. However, if the player achieves his secret height, he gains more points the greater the diviation.

I hope this makes sense... here's a quick example.

3 Towers (A, B, C).
Game height requirements:
A - 2.
B - 3.
C - 5.

3 Players(1, 2, 3).
Players secret height requirements:
1 - (A, 4) (B, 3) (C, 1)
2 - (A, 2) (B, 5) (C, 4)
3 - (A, 5) (B, 2) (C, 3)

Finished Towers:
A - 4.
B - 3.
C - 3.

Co-op points vrs Comp. points:
A - All players lose co-op points. Player 3 loses more points than player 2. Player 1 gains comp points. (Which are greater than the co-op points lost).

B - All players gain co-op points. Player 2 loses more points (which are greater than the co-op points gained) than player 3. Player 1 gains comp points.

C - All players lose co-op points. Player 1 loses more points than player 2. Player 3 gains comp points. (Which are greater than the co-op points lost).

I hope you get the idea. Basicly, do you go for co-op points? Or do you gamble that you'll make your secret goals, thus hurting everyone else but yourself? The greater the diviation between the co-op goals and your secret goals the bigger the pay off, but also the greater the risk.

Now, this sounds like it could be pretty fun. I just have no idea how to build a game around this mechanic. :( (Not to mention any sort of theme)

All comments welcome.

P.S. Towers would begin the game at the "medium" height.