No, this is quite common. They have ads now which are just webviews that open an HTML\JavaScript version of a small slice of a game, often Game of War or similar generic RTS\tower defense mobile trash. Apple actually does allow this app-within-an-app method of code downloading if it's just a webview. They actually force you to not just watch but actually play and progress in the game for about 20/30 seconds (i.e. add play one short round of tower defense or drop a few units on the ground and fire at enemies) before going back to the app.
I'm trying to find an example of a game with it so you can see for yourself (I would assume many Android games have the same thing), but it seems I've uninstalled them all out of frustration.
I'm trying to find an example of a game with it so you can see for yourself (I would assume many Android games have the same thing), but it seems I've uninstalled them all out of frustration.