I think it would be better if the 400 achievement gives +200% and 500 gives +300% instead of +100% and +400% respectively. It gives a better growth rate in line with 200 and 600 achievement and increases profits by a bit .
I can't be the only one who tried to fill in the darker squares leaving the lighter ones empty... I wish the color scheme made more sense, or at least if a supposedly empty square is colored it glows reddish or similar instead of being almost the same shade as an uncolored white square.
If the bonuses didn't just stack additively, that would be great. In other words, +50% power would add 50% of the current power like in IE 1, not 50% of base power. Same goes for money/XP boosts. And allow us to change the color scheme, or base it to reflect the location reached, or unlock new ones with new locations to better show progress and improvement. Paper gray looks more prehistoric than futuristic. Also, the capped auto speed making the bought clicks worth 2/3 of income and power being the only effective upgrade later on are just more reasons I actually liked the first one more.
It would be nice if Angel Investors stacked exponentially instead of just adding up because as you progress each AI requires more cash and the % increase in profit compared to the previous reset decreases if you reset at uniform intervals. But innately that would make early AIs insignificant and later one OP. Instead, maybe after an AI milestone, give an upgrade to switch an AI (stackable like businesses) from +2% amongst several 100,000s to separately multiplying by maybe a smaller amount. It shouldn't break the game or your computer as the upgrade cost would also increase exponentially.
It should be stated clearly in the game, for example before/during tower defense levels that tower weapons require you to hold down the mouse button unlike the personal click and shoot weapons. Or you could just allow auto-fire when using towers, since tower weapon reload times aren't shown, timing powerful shots aren't practical anyway. And enemies killed by your minions/mercenaries should at least drop a fraction of the gold, or just make it that ally kills do not count towards combos but still give gold.