Steam Greenlight is a platform for developers to submit games for potential sale on Steam, requiring a one-time fee and adherence to legal and ethical guidelines. Additionally, the 'Indie vs PewDiePie' initiative invites fans to create games for the YouTuber's channel, allowing for a competitive atmosphere, while the Global Game Jam hosts an annual competition for game development over a weekend. Each initiative emphasizes ethical constraints like the prohibition of offensive content and has specific time limits for submissions.