Okay, having played it a bit more to give a fair assessment, and then playing a bit more because it's quite fun, I bought the golden axe as I felt I ought to pay something toward my entertainment.
The main structure of the game is fight, die, upgrade, retry, eventually upgrading enough to pass one checkpoint and get to the next, where one is likely to die again until upgraded. That structure isn't itself bad, but I'm very sceptical of such in mobile games when there's an option to buy gold (upgrade) because I anticipate the game balance to favour parting with real cash to get anywhere. After playing for a bit and finding that it's perfectly possible and reasonable to upgrade via in-game winnings, especially with the golden axe, the mobile-ness PayToWin mechanic clearly isn't an issue.
As with all these games, the major long-term interest comes from unlocking new units. Unit variation is a bit lacking IMO. The healers, for example, are nigh useless, taking up an valuable combatant slot and killing themselves when they heal someone. As units can be spawned at highest level with town upgrades, keeping them alive is unimportant, so the heeler is redundant. Once the wizard is unlocked, all other units become redundant until maybe some of the later/more expensive ones. Long range + interrupt + knockback means constant strafing runs kill all with little retaliation. I've found no need to mix-and-match units and apply tactics.
The mechincs themselves are fairly classic arcade, which is a Good Thing in this age of single press games, mostly about dodging bullets. There are a couple of strategies to experiment with, like 6 top-level Engineers leaving turrets at the spawn points (spawn killing FTW!). For a little time filler, it's pleasantly entertaining. The virtual thumbstick is a good idea, although adapting to it took time. I guess that's an issue with touch screen thumbsticks. The stick appearing whever you press is good as it makes corrections for drift very easy (replace thumb!).
Production values are sweet, with great little characters. Audio bugs me! Too noisy. But when I turn off the BG music, that also disables summoning riffs which is a little odd, seeing the Bard playing silent guitar. I suggest moving the guitar riffs to the Audio FX channel and muting music when they play.
Gotta go to work, but I keep putting off my post and feel I ought to say
something! It's a good game that seems to be reasonable popular - I hope it pays off for you.
