Thanks for the fully thought out review, tons of great feedback! I think the for the starting enemies (Spiker & Tanker) those ideas are great, and for the tanker I will try to put the first damage upgrade infront of the enemy instead of after it. This which would most likely solve them from being overpowered with no damage upgrades as you said.
For the economy, I wanted to make all of the enemy upgrades MUCH cheaper so it was easier to progress (And faster), I'll do this in a later update after the jam. The knockback is kind of weird, sometimes the enemies seem like they instantly teleport, so I'll definitely do some changes to it (Also might lower boss hp or find a workaround).
For regen I also find in lategame it can be op, since you regen 4% (I think) of your max health a second, but I think its good so it's harder to die late game which can be really punishing. But like you said, it might be a little bit TOO op and I might think about lowering the max regen amount, or maybe making the upgrades more expensive, or having a special, optional branching upgrade that isn't necessary to buy.
Also about your major nitpicks, I definitely found that to be a bit of an issue (Mainly the maxed upgrades). I'm pretty sure I was almost going to add this, but ran out of time. I did kind of have a way of communicating that the upgrade was maxed via the outline, but adding the "MAX" Text would not be very hard to implement and a great addition! Also about the "<- BUY" text in the tutorial, I will add a thing so it gets removed after buying the first upgrade.
Again, thanks for the great feedback and some things I will definitely implement once the jam is over! Here's a little post I have for future plans: https://mydimons.itch.io/spin-blade/devlog/1001546/future-plans (Just updated it from these awesome suggestions)
Amazing!
As for putting damage upgrades in front of the Tanker--I'd suggest at least doing it in parallel rather than as a requirement to unlock them. Otherwise you're essentially lowering their health, which kind of negates their special property!
I think giving the player CHOICES on how they want to progress is the fun bit. Even something like exposing enemy stats instead of suggesting a strategy might put more power into the players' hands to make their own choice and live with the consequences. If there's a big number in the HP stat, with maybe a description like "defensive shapes" or something rather than "go buy damage before buying this!", it will make the player feel more clever when they decide to prioritize the damage upgrade first!
I think making enemy upgrades cheap to encourage progression is a great idea. I didn't notice that, but I think I enjoyed the game more because of it!
Check out the game Nodebuster if you haven't -- it has a unique "combat" system and a nice progression. The shop has a good system to represent the bazillion states an upgrade item can be in.
I have tried Nodebuster (And finished it), and after a day of working on this game I realized how similar it was and then started to take inspiration from it (This is why I added a skill tree, but put my own twist on it with the enemies).
For the damage upgrade in from of the tankers, I think doing it in parallel would be a good idea, but for the upgrades after the damage & enemy, you would either need to have both upgrades to unlock the next upgrades, or have the enemy unlock a new branch of cool upgrades.
Also implementing more choices with completely optional upgrades would be very cool, I've had some people suggest paths that will lock another one (Someone gave the example of giving the saw a fire or ice upgrade, but you can only choose one)
Thanks for EVEN MORE amazing feedback!