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Out of all the gaming hardware I own, Sega's Multi-Mega / CDX is one of the most treasured – mainly because it's such a cool and sleek device, but also because, as a kid, it was totally out of my price range. This perhaps applied to many other Sega fans, as it didn't sell particularly well when it launched and is now a sought-after collectable.
I managed to pick one up recently and it cost a small fortune, but there's one glaring issue when it comes to owning this all-in-one console in 2026 – you can't run CD images from your flash cart as the cartridge itself causes a conflict with the bus that the Sega CD hardware is accessing.
If your setup includes the Mega Drive / Genesis and Mega CD / Sega CD, then this is easily solved – you just uncouple the main console from the CD-ROM add-on. However, because the Multi-Mega combines the two systems, you can't use this workaround to run CD images from your flash cart.
Thankfully, modder Zaxour has produced a mod kit called the CDX Engine Idler which finally solves this issue (thanks, Retro RGB).
Retailing for $50, the kit requires a quite complicated installation procedure, so you might want to enlist the help of a professional (I got my Multi-Mega region-modded by the always brilliant Simon Lock, who informed me that working on this particular system is quite a challenge due to its small size and the amount of tech Sega crammed inside).
Granted, there's a very small pool of people who might require this mod – it's probably cheaper just to buy a second Mega Drive / Genesis and use that for booting your CD images via flash carts – but at least the choice is there if you want it.