The phone company in question almost certainly has aliens working there in the game, but not necessarily alien mindbenders. (Sorry ZakPhoenixMcKracken)
It was an electronic advertisement, and quite blatant. Anyone who played any significant amount of the game would definitely have seen the ad prominently placed on the screen multiple times during gameplay during events appropriate to the ad.
That’s definitely not the game I was thinking, and I was only thinking an ad in the game, rather than the whole game being an ad. But the revelation of a phone company adventure game is so amusing and educational, that combined with the fact that the company’s name is right there on the title screen, I’ll accept it as a valid answer. Your turn to pick an item.
I’m pretty sure that I have not played the game Caven is thinking of, so I have focused on that advertisement poster I was talking about in a previous post and I have realized that the game is “Secret Files: Tunguska” (which is an undervalued game, in my opinion).
I have been able to remember it only in an indirect way: I remembered that the “evil corporation” featured in that game is also a phone company and at that point the connection to the ad was easy. It is a simple poster ad on the wall of a street.