The MSX is an 8-bit home computer released mostly in Japan by ASCII and Microsoft. It has very similar hardware to the Colecovision and SG-1000 both graphical and sound wise. It was Japan's massively successful console before Nintendo's Famicom came along and dominated the console market, while the MSX continued to have steady competition with other home computers such as the NEC PC8801. The MSX2 was later developed and saw massive success with Hideo Kojima's Metal Gear and Metal Gear 2: Solid Snake.
Tile Layer Pro
The MSX and MSX2's graphics are very simple and are usually easy to find within a basic tile editor.
YYCHR is a good alternative if you want a more sleeker looking program, it has all the same functionalities as well.
BlueMSX has features such as save stating and internal pausing, however it is quite difficult to run MSX2 disk games due to the lack of clear instructions online.