So the key to a very fun game of mental omega is surprisingly money. Of course, many people here will jump on the idea of "fun" and say it is subjective.
So, what defines a fun game?
Out thinking your opponent.
Trolling your opponent.
Outmaneuvering your opponent.
What is NOT fun? Spamming units. Mindlessly clicking build queues to get an army capable of bashing the enemy.
So... spies? very much fun.
Spamming tanks? Not so much.
Spamming borillos? Not at all.
Picking off your opponent's harvesters and forcing him to protect harvesters? VERY FUN.
Mass producing carriers or reshefs to spam the enemy into the dirt? Flashy... but tedious.
However, the trick to a "fun" game is the economy. The more $$$ flowing in the game, the more spammy it gets. Also, the AI seems to have unlimited supplies of cash, or does not burn cash to create units. And that is a shame. When there is alot of cash, you produce dogs. You don't ask if there are engineers. You produce dogs to kill potential engineers. You also produce engineers and don't ask if there are enemy dogs. You spam. You don't counter.
Same for all kinds of units. When you have cash, you mass produce.
So, the trick is to keep the cash flow very very low. The closer to starvation all sides are, the more strategic they will be about spending money.
An ideal economy would have no new ore mined. Once the ore is all mined, that's it. You are done.
Alternatively, it would have ore generation, but no initial ore deposits.
Both options yield interesting drawn out games that require critical thinking, maneuvering, and subtle spy games to win.