I like the concept but the balance is frustrating. The only upgrades that feel like they do anything is when you unlock new people since they give a good amount of money despite needing more hits. But even then the strategy goes from following random people to following the latest person you unlocked. Several upgrades, which means several rounds since the price is kinda high, of unlocking range and user count and I go from maybe hitting two people once per round to maaaaaybe hitting 2 people 2-4 times per round. This is after roughly 20+ rounds. which because they need 3 hits each means I might kill 1 extra person 2 if I'm very lucky after 20+ rounds of upgrading. That's not good. With games like these you want to feel like upgrades do something, especially in the beginning. Which yes, I did focus on increasing the amount earned first. Also, making the attack rate scale with heat is a bad call. After my rounds got increasingly short I just avoided all upgrades that added heat. You have a good concept but I'd really work on balance. Maybe add a damage upgrade early on since I never felt the need to increase spawn rate.
Thanks for the detailed feedback! I agree that the progression curve is not steep enough in the beginning. I need to work on instilling a sense of power earlier.
Regarding attack rate being tied to heat: This is only in some upgrades - the more powerful ones, so they have an upside and a downside. The heat problem can be solved with other upgrades though... but still, there is a lot more balancing that would benefit the overall gameplay.
Thanks again for your constructive criticism! I'll incorporate this in the next version.