I've been playing Nuke for Brainrot almost every day since it launched, and the one thing that caught me off guard early on was how unforgiving the upgrade timing is. Upgrade too early and your cash/min dries up. Wait too long and you're stuck farming B-tier brainrots forever. So I started tracking obsessively — cash before/after each upgrade, income per minute per brainrot tier, time between upgrades. After roughly 15 hours across multiple server runs, here's what I found. The Nuke Upgrade System, Explained Simply The nuke is your progression gate. Each tier lets you break through higher-rated walls, and behind those walls are spawn zones for rarer brainrots: Basic Nuke → Tier 1 walls → Common/Uncommon brainrots Mk2 Nuke → Tier 2 walls → Uncommon/Rare mix Mid Nuke → Tier 3 walls → A-tier brainrots (first real income jump) Advanced Nuke → Tier 4 walls → Full A-tier + early S-tier Ethereal Nuke → Max walls → Secret ultra-rare zones No premium currency needed. All in-game cash from brainrots in your base.…