Let’s clear the air.

Complete the required repairs, then defeat the season’s boss. Spring: Glitchgeist. Summer: Infernaut. Fall: Moldar — repair the flooded factory. Winter: Kryonnix — restore mountain heating.

Each level has two concealed side rooms. Explore out-of-the-way ledges and suspicious masonry; three attacks can break a sealed entrance. Press Up to enter. Inside, take the upper platform route for a 500-point golden wrench, or cross to a unique restoration worth another 500 points. Time your jumps past the vent, and hold Service at the restoration. No filters are needed. Up at either doorway returns to the level, even if you skip both rewards. Explore before entering the boss arena. Collect the limited filter packs; each shows its quantity. The total supply exactly matches the systems that need filters, and packs do not respawn. Sabotaged units reuse their installed filter when repaired again. Hold Down or S to duck on land and dodge high shots; Down still descends ladders and swims downward in water. Spray bottles upgrade your attack. A cape lets you tap jump repeatedly to fly; taking damage removes your weapon upgrade, cape, and Snow Boots. Follow the filter markers. Jump on rivals or use your wrench. First hit squishes an enemy; the second defeats it, even while stunned. Stop saboteurs before they undo your work. In Summer, use fire escapes and rooftop jumps; watch opening windows and recover stolen filters by defeating robbers. In Fall, fix leaks to stop water rising, then swim down and clear drains to empty each basin. Use up/down to swim; tap jump to stroke upward. In Moldar’s arena, hold the service action at spigots to open them. Hit Moldar to interrupt him shutting valves. He can also pull the floor drain; hold service at it to close it again. Moldar keeps moving more slowly underwater. Hits deal ¼ damage above water and full damage when he is submerged. In Winter, use opposite-direction input to brake on slippery hills. Repair lodge heaters with filters. Jump between floating ice and watch for salmon, skiers and snowmen. Start with your wrench. Collect snowball piles to deal twice the damage. Snow Boots allow a short slide, improve hill grip, and are lost when you take damage. Three single-use heart pickups per level restore one heart each; they stay available when your health is full. At zero hearts, choose Continue to resume from your checkpoint with five hearts and completed repairs saved. In the ice cave, hold service beside outdoor heaters. Keep them lit to melt the ceiling: four avalanches defeat Kryonnix. Shoot down his ice projectiles before they freeze the heaters. Hit a streetlight’s checkpoint sign to turn on its lamp and restore your hearts.