Q: Do I have a case for Unjust Enrichment, Idea Theft, Misappropriation, etc?

A: You're dealing with a complex intellectual property situation that intersects with contract law and technology. Based on the timeline and details you've shared, pursuing legal action could be challenging due to California's statute of limitations, which typically requires claims to be filed within a specific timeframe after discovery of the alleged misappropriation.

The success of your case would largely depend on whether you can prove the corporation had an implied contract with you when they acknowledged your email, and whether your blueprint contained sufficiently novel and concrete elements beyond general ideas. California courts generally don't protect ideas alone, but they may protect unique combinations of features or specific implementations that were confidentially shared and subsequently used without compensation.

Your best approach would be to consult with an intellectual property attorney who can review your archived evidence, especially the contemporaneous documentation of your blueprint and the corporation's acknowledgment. They can help evaluate whether the similarities you've identified are legally substantial enough to pursue a claim, and whether the browsewrap terms of service from the third-party platform could strengthen your position regarding ownership rights. Consider gathering all your documentation, including timestamps of when specific features appeared in the game after your submission, as this timeline could be crucial for your case.