Hi, you have a nice base here, simple and to the point. Here my feedbacks:
Couple UI fix IMO:
- Make the Spd + button clickable, you point an arrow to it but it does nothing.
- Make a different icon for the turrets upgrades page and the basic turret page. Kinda dumb from me, but I though I should've two basic turrets since there was two basic turret icons.
- Also I am not sure about the layout of the upgrade page/tab icons. You have one "tab" for the wall upgrades and one "tab" for turrets upgrades, but every turrets then have a "page" for their upgrades. If you plan to have different kind of wall page upgrades, you should distinguish "tab" and "pages". Either group them like [ A | B ] [ 1 | 2 | 3 | 4 | 5 ] or separate them like [ A ][ B ] | [ 1 ][ 2 ][ 3 ][ 4 ][ 5 ]. If you don't plan to have wall page upgrades, you could just put them all at the same level and remove the distinction between wall & turrets: [ A ][ 1 ] [ 2 ][ 3 ][ 4 ][ 5 ].
About Gameplay:
- The "closest" and "random" target is nerfed by not reseting the target after each shot, if at some point the strongest enemy becomes the target it doesn't let go. I don't know if its by choice, but it removes some of the agenda players have.
- I think the Shotgun firerate shouldn't scale as fast as the Machin gun. Maybe it shouldn't even scale since pellet count is also a firerate upgrade in a way. You could replace it by effective range.
- In your game, wall upgrades are irrelevant because the best damage mitigation is simply to clean the field before enemies touch the wall. Whatever money spent in wall upgrade is money that doesn't progress the waves and that would be lost by any power creep. With enemies making only 1 damage, 20hp is already really forgiving and with 1 upgrade in repair, we fall in the dps race kind of defense, and the turret are wining. You could start with 1 hp and set one-of or fast capped upgrades like max +2 hp, max 1 Regen per wave, 1 screen clear per reset (or any damage buff mechanic), temporary immunity...
Gameplay additions:
- One way tower defense idle games usually balances themselves
is by letting the player upgrade the enemies. Like making them harder to kill but giving out more money. (they should be able to cancel them to not softlock themselves) - One way to nerf damage output is to makes it irrelevant from time to time. For instance by giving Hearthstone style "divine shield".
- Your Spd+ meter is a good idea you could exploit on multiple axis: You could have upgrade for it, turret upgrades that only scale with it, or choice between different meters payoff (like an temporary overdrive that put the meter in cooldown)
I believe you have a difficult framework to work with here: Player agency is mostly comprised of upgrading firepower. And your leverage of balancing the game is enemies stats and costs. Meaning the balance is pure maths. Which won't really be fun for you nor for your players.
Of course maths are important in idle games, big numbers go big, one number goes many numbers. That's the juice.
Yes, you could start by making enemies a lot harder to kill or output enemies faster, since you don't really lose anything by dying except time. Unless you want a good player to "win" from a fresh save without reset.
But I think you should also find a couple other avenues for player agenda. You could have double edged upgrades for enemies. You could dig deeper into the idea of idle runs for money gathering and active runs to reach higher waves. You could add walls or zones at different level of the screen with other effects and cooldowns.
Good luck and congratulation.