Wow! That's an interesting map! I love Mario Parties, I've got 'em all except 2. So, I think I may be of help.
BTW, I never thought of combining it with a defense part, but it really sounds great.
OK, man, you need some KEYBOARD games. Loads of MP games are simply pressing a button, and you can take advantage of this 'coz keyboards have loads of buttons.
I'll give you an idea of a mini-game, and it's 2v2
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OK, first of all, you'll need Gateways. Why? Well, you need 'em 'coz they don't lift up and they don't need larvae. What to do? OK, make sure players can produce all 4 units a Gateway can produce (Zels, Goons, Templars and DT). You can give them stacked buildings so that they occupy not so much space. OK. Now for the mini-game.
I don't remember the name of the game, but I know it's in MP3. OK, what they did is that each team needs to cut down wood logs. Logs are named with the controlers buttons (A, B, Z). One of them holds the log and the other cuts it. To hold you need to press the button of the log, and the cutter, once the player is holding it, too. The team which cuts the more logs in 60 secs wins.
OK, how to SCise it? OK, you distribute the teams and give them Gateways. You divide the battlefield into two (not the terrain). Randomly, com units should appear, being these Zels, Goons, HTs or DTs. One player has to push the right button first and the other the second. If they both push the correct buttons, they get one point. And then all over again (Hyper Triggers needed) If one of them makes a mistake they won't score a point. As you see, hot-keys are essential.
Well, I think this could be a great way to have games, I'll soon come with new ideas.
See ya!
Richan