Well, with an alarm you could still set it up to go off within 15 mins I'd assume; fairly useless to be sure, but at least it'd give you a way to test out the app's reliability. What bothers me about the 15min limit, is that sometimes the first-time setups/downloads for bigger games already take about 15mins to finish, leaving you with virtually no time left to actually try them out. I know this happened to me with Dungeon Defenders even though I was on wifi while it downloaded its assets. I didn't mind it too much cause the game was decent, but I could easily see this not being the case for other people buying similarly large games.
