Can i expand a little tutorial from unity into a much bigger game and then sell it?

Recently I started to work on unity’s survival shooter tutorial and I REALLY like the Idea behind it…I would really like to use the assets from the tutorial, assets of my own and the idea of the game to make a MUCH bigger game, can I do that? is it legal?

Yes, it’s legal. I would strongly recommend ever releasing such a game though. Unity has millions of users and its assets are instantly recognizable by players across the globe. If you attempted, for example, to release a game on Steam using standard assets your reputation as a developer would be decimated by negative player reviews.

Why not hire or team up with an artist to create original graphic assets for you, using the Survival tutorial as a reference?

The main thing you want to avoid is plagiarism. Make sure you represent it as a mod.

The reason is, it’s semi-common for dishonest people to do that, then use it as a demo of their work (like for job interviews,) and imply they did it all themselves. This “trick” is so despised that you don’t even want to look like you’re attempting it. Even if you just want to work on free projects, you don’t want a google search by a potential teammate to turn that up. If you added new missions and 3 new weapons, just say that. People will understand and respect that. If someone adds a comment to your game “this is a rip-off of a tutorial level” you want the next comment to be “duh - it says it’s a mod in the description. The new levels are good.”