This World Is Mine is a bit ambiguous. For some of the races who arrive (Burlusts!), they absolutely will be very aggressive. If you aren't, the morale of them will go down and you'll have problems. So if you choose Burlusts, you had either better be renting them a lot of violent movies or else sending them to war, heh.
If you're playing as someone like the Peltians, of course you can still be warlike, but they aren't very good at it. Still, there is a matter of acceptance that you can have "this is our town" sort of a vibe, if you see what I mean. Rather than being aggressively claimant, it's more a matter of a statement of belonging to a new place. Frankly, depending on how someone says it, it can be a little wistful/sad, even ("I can't believe THIS world is mine..."). I see that as kind of the Evucks, heh.
And then, as Draco18s points out, it's also something The Entity very aggressively would say. Well, welcoming at first, actually. But aggressively later, depending on how you play. One of the victory conditions is actually escaping from the clutches of the world, getting back to space. Another is blowing up the planet to save the galaxy from the entity, even at the expense of your own life (and everyone else on the planet). Others revolve around doing what the entity wants, or meeting your own goals despite the entity not approving. So in some respects I see this as a very ominous sort of statement, kind of like "There was a hole here. It's gone now." (10 points for anyone who gets that reference without looking it up).
In terms of it being kind of whimsical/humorous, that is true, and that is somewhat unfortunate. It doesn't really match the tone of the game per se... but then again, there tends to be some darkly humorous aspects to all our games, and I expect this will be no exception. I'm also hoping that title says "this is a fun game" rather than "this is a spreadsheet where your eyes glaze over," which is an important message for this kind of game, heh. So I think it can fit, particularly if the scary entity voice says the title in the trailer in a scary way, and if the logo itself looks dangerous/scary rather than whimsical. Just seeing the name by itself defaults to seeming a bit funny, but no exclamation point will be forthcoming.
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