Offline tournament "Evil Lands".

So, what does the task say? We need to eliminate all the "colored" ones, and we don't necessarily need to capture neutral objects, right?

Well, it's basically a speedrun.
And the win condition is original – eliminate all the AI opponents.
Therefore, using the method of induction, we can conclude that eliminating neutrals is not a "sufficient" or "necessary" condition, but...
In short, you messed around and lost. Eliminating neutrals is not required. :)