|First Game||Samurai Spirits|
|Last Game||Boogerman II|
Rex Soft (雷克斯軟體工作室) was a company that released a number of pirate originals for the Famicom during the mid-1990s. These games share a sound engine and fonts (the latter taken from Borland BGI) with most of NTDEC/Asder's original games, so were probably created by at least some of the same development team, but it is unknown whether they were produced under Asder.
Rex's first known game, Samurai Spirits, was released on a board containing a Huang-1 chip usually used by Someri Team which indicates it may have been manufactured by Ge De Industry Co. - if Asder had published this game, they presumably would have manufactured their own board. As Asder itself appears to have stopped developing Famicom games after about 1994 to focus on educational software, Rex may have been composed of developers who left around that time.
- Boogerman II (1997)
- Dragon Ball Z 5 (1995)
- The King of Fighters '97 (1997, later hacked to make KoF98 and KoF99) - exists in full and cut-down versions, the latter lacks the final boss and ending and just loops infinitely.
- Samurai Spirits (1995) (later rereleased as Samurai Shodown III)
- Boogerman II, Samurai Shodown III, and King of Fighters '97 were released with cartridge labels crediting "S.M.I. Co., Ltd" with a date of 1996, despite the in-game copyright date in all cases being 1997.
- Boogerman II has the ID NSM-001, Samurai Shodown III is NSM-002, and King of Fighters '97 is NSM-003.