2 minutes ago, warmer said:This wouldn't apply to a game written in an engine version prior to this being part of the contract entered by the dev at the time of game development. The contract can only be moving forward from point of game dev. You can't apply a contract backwards in time. That is a core tenant of a contract, and why a date is associated with one in the first place. If you continue to develope a game after using the version of unity's EULA associated with the you are agreeing to it.
There are so many reasons why you can't write a new rule to create a fine, and retroactively apply it to someone's previous work created prior to that established clause.
I haven't read their fine print and don't plan on it. However, it is quite likely they have in there that the pricing can change at any time. That doesn't require a new version or new contract. It of course depends on how it is worded. Whether it's worded to allow such a change is something lawyers would need to determine. I'm not a lawyer and most (perhaps all) people here commenting on this aren't lawyers and so cannot state for certain what is or isn't allowed based on their terms of use. If they push this through and it is retroactive, then that will answer the question of legality.