Amazon.com announced a new One Up Your Game promotion this week that will let video game fans buy a select Xbox 360 game title now and then trade it in towards the same game (or another select game title) for the Xbox One. The cost is only $10, roughly, but can vary according to the trade-in value assessed.

It seems like a pretty good deal. But boy are there a lot of caveats and conditions. And a lot of confusion.

First, the trade-in offer applies to just 8 games, though each is a coming A-list title. These include Madden NFL 25, Call of Duty: Ghosts, FIFA 14, NBA 2K14, Battlefield 4, Assassin’s Creed IV: Black Flag, Watch Dogs, and Need for Speed: Rivals.

Each customer can only perform one trade-in.

And you have to do this all between now and December 31, 2013, which is kind of a time crunch since none of the eligible Xbox 360 games are even available yet. Instead, each is available for pre-order, with the release time frames varying from late August through November. Given the November release date for the Xbox One, it may make the most sense to order a game on the earlier side of that schedule. (For example, there’s a reasonable chance that Call of Duty: Ghosts will ship the same day or week as does the Xbox One. So that might be a bad choice for this.)

Confused? Me too.

Here’s how I think it works. (Amazon’s instructions are a curious combination of long and vague, sort of like the instructions you get with IKEA furniture.)

First, you purchase one of the qualifying games for the Xbox 360. It will arrive eventually and you can begin playing the game on the Xbox 360.

Then, sometime later in the year—perhaps your Xbox One has arrived—you can trade-in the game, which involves mailing it to Amazon (really a third party partner) “for processing following the instructions provided.” You need to wait for this to happen, and during this time of course the game is gone and you can’t play it.

When the trade-in is accepted, return to the One Up Your Game page on Amazon.com and add a qualifying Xbox One game to your cart. Amazon says your bonus credit will be applied automatically to your purchase.

Still confused? That’s understandable. Because according to Amazon, the Xbox One game version upgrade is just $9.99. But the firm also notes that each Xbox 360 game trade-in receives a “trade-in value of at least $25” plus a $25 bonus credit. So while the base offer is $25 + $25, or $50—meaning that the $60 Xbox One game you’re trading up to can be had for just $10 ($9.99), it’s theoretically possible that you will receive more than $25 for the trade-in, right? It does say “at least $25.”So you could theoretically get the game for less than $9.99. It could even be free, assuming this thing isn’t rigged.

I don’t know. :)