I tried a new Leaderboard implementation this time around as my old standard went Paid Subscription only. The backend is just a Google Sheet with a tiny little Web App hooked onto it. Unity reads and writes to that url via a standard UnityWebRequest. It took one afternoon, excluding all the juice and fluff I later piled on top of course. Recommended!
As for how the powerups work, each one has custom "Ammo", might be bullets, might be seconds. If you grab another copy of one you already have, it adds to ammo remaining. If you grab a different powerup, it's totally separate than any you already had. Some do last longer than others - but also some are more potent than others (🧲👑).
Two to Four Powerups at the same time with an occasional drought seemed about right to me without trivializing the experience, so that's typical but not a rule. I kind of wanted the game to bounce between Bullet Hell and Bullet Heaven, Prey becomes Predator, ala Pac-Man. The Snake also speeds up as the game progresses, so you can actually achieve even more simultaneous powerups the further you get, which is real good because the enemy swarms get nastier over time too.
Thanks for playing! I always look forward to your submissions :)