I guess because this was the Version that was first released on Steam; only after restarting and verifying the game-files you had the actual 1.0 Version. And it seems HI2U took the first Version and released it. Maybe it was a move from the developer to outsmart the warez-scene for the first couple of hours. Or it was a simple mistake. But I would bet on the first possibility.
looks like this HI2U release is an older build; it shows version 0.666 in the corner; the game was released this way on Steam today; but on Steam you only need to restart the client and verify the game files; THEN the game shows nothing anymore in the corner. As far as I read the folks over on Good Old Games are still waiting for that updated version (Edit: Version 1.0 is out now on GOG as well). I don´t know what else, if anything, changed from one version to the other.
how old is your hardware!?
seriously.
edit: I checked...this is an old build...why?
Can't wait to try it out. :)