(Image credit: Xbox Game Studios) Forza Horizon 6 has been one of the top sellers on Steam since early April and it's not even out yet. As of April 15 it had reportedly been pre-purchased more than 500,000 times, and that's likely to have nearly doubled since, considering how steadfastly it has hovered around the top of Steam's weekly revenue charts. It's a pretty astonishing figure but, for some context, Battlefield 6 was reportedly sitting on around 1.7 million pre-orders in the week before its October 10 launch. I would never pre-order a digital game, but it's interesting to consider the reasons one would. All Forza Horizon 6 pre-orders get a bonus "Pre-Tuned Ferrari J50" which is hard for me to get excited about since the full game has over 500 cars. Pre-orders likely have much more to do with the $120 Premium version, which grants four days early access to the game and all future DLC.…