Note for my Gameplay Time: I have played this a bunch on iPad- it was my go-to "toilet/waiting room" game for a few months. As it is the exact same game on Steam, I thought I'd toss my opinion in. I am giving it a positive review- but please read, as it succeeds in what it is trying to do but it is a very specific goal.
PROS: It is a perfectly functional mini MOBA. Everything works very well, there is little to no waiting for matches, and it seems balanced well. If there is a pay-to-win aspect I certainly haven't seen it as I've never spent a dime and have a roughly 70% win rate.
CONS: If someone, for whatever personal reasons, wants an extremely simple MOBA to play on PC- this would be a great choice. However, if you want in-depth gameplay there isn't much reason to play Solstice Arena. The graphics look good on iPad but are nothing special, very basic, on PC.