Some sad news, but a silver lining: The indie developer of Waves and Waves 2: Notorious has passed away and as a parting gift has made his games free to play/own.
Waves on Steam
Waves is an Arcade Twin-Stick Shooter that's all about High Scores. Build your combo and drop bombs in pursuit of Leaderboard dominance over seven game-modes!
store.steampowered.com
Waves 2: Notorious on Steam
Waves 2: Notorious is an arcade twin-stick shooter set in Cyberspace. Build Combos, earn Adrenaline and unleash powerful Burst attacks as you Dive into the Net and do battle against an AI that adapts to your weaknesses!
store.steampowered.com