iMSX 2.8: the MSX emulator lands on Apple Watch
Playing Vampire Killer on a watch is now possible. According to Time Extension, developer E7 Company has released iMSX 2.8, which adds an Apple Watch app to its emulator of ASCII's MSX computer. The article's author admits the idea is niche, but fun.
It works through the iPhone: you send ROMs, disk images and saves there, and they sync to the watch. The game then boots on a miniature screen with programmable touch controls. Titles mentioned include Vampire Killer, Aleste and Metal Gear 2: Solid Snake.
A more comfortable iPhone version
iMSX is built on C-BIOS to recreate the MSX platform, and also runs natively on iPhone, a handier option for everyday play. The app sells for $2 / €2 on the App Store (search for "iMSX" by E7 Company); since no direct link could be verified, use the App Store search. As always, only use ROMs and disks you legally own.
Source: Time Extension