For $2 minimum you get game War of the Human Tanks, 100% Orange Juice (+ Sham & Sherr + Acceleration), Sound of the Human Tanks. For $7 minimum you also get QP Shooting - Dangerous!!, 200% Mixed Juice!, Neko Navy, ManaCollect, War of the Human Tanks - Limited Operations.
For $25 you additionally get Lionheart, ENIGMA:, Miniature Garden, Magical Eyes - Red is for Anguish, Sora.
Get the bundle here!
Each game is delivered as a Steam key. All of them are playable on your Windows PC.