beating the game isn't particularly difficult once you realize that flowers play a major role;
while higher level towers have better skills and far greater damage output, lvl1 flowers seem to be the only way to increase the range of towers, which greatly increases your overall firepower, allowing the stronger towers to be active on a wider area.
the randomized nature of the game keeps it interesting, although it gets really tedious when trying to complete specific achievements which require some serious rng luck.
one basic strategy is to fill the board with towers, then upgrade the ones in the middle to the max, then merge everything else while leaving flowers alone.
the only mild complaint i have is that the available tower positions are kind of weird?
aside from the obvious ones, there's some extra spots all the way to the bottom of the middle column, while you can only place a few near the spawn point, where it feels like there could be more.
having the towers description popup show up in the bottom also gets in the way of seeing some of the placed towers;
basically a map redesign could be considered.
any tips for the 30 quest medal?
i managed to clear 29 quests but only got 4 of the 5 towers for the last set.
you can't exactly make 5 of the same lvl 5 towers without selling everything else due to the randomized nature of the game and limited coins you have to work with.
maybe increase the rewards for the higher tiered quests? it seems you get 250 coins for each quest completed, regardless of the tier of the towers, which feels kinda underwhelming especially after getting 5 lvl5 of the same type all at once
edit: tried making some kind of guide to help with the quests
https://www.newgrounds.com/dump/item/4c437e72380c37575ffa68085f6959d8
also for the "master of the coin" medal, the coin total on the final result screen is irrelevant.
the actual requirement is holding 25000 unspent coins at once, so you basically need to roll really good upgrades (mainly lots of early shop upgrades) and at the end of wave 29, right before the final boss wave, sell everything and hope you make back more than 25k coins