The section titled “User Generated Content” found here: https://www.modd.io/agreement/tos/
“grant[s] Mod Studio a… worldwide license to User Content (characters and character names, text, data, logos, graphics, sounds, videos…)”
Essentially this clause gives mod studio full rights to a user created game and its assets. This prevents developers from using assets purchased from an asset store in their games as is common in indie game development. Store bought assets are licensed to the developers and they do not have the right to grant mod studio a license.
This means any game would either need to use public domain artwork, the limited artwork found in mod studio, or create their own artwork and give it to mod studio for free. These terms substantially hinder the options for creators on this platform.