openMSX is an open source emulator of the MSX home computer system.
By default, it comes with a minimal firmware rom, known as c-bios, which enables you to run most cartridge based MSX games.
In order to run such a game, you can copy a dump of the cartridge onto the storage memory of your Android device and then insert the so-called ROM into the virtual cartridge slot of the emulator using the on-screen menu that you can open with the standard Android menu key.
You can also install the firmware of your real MSX into openMSX. See
http://openmsx.sourceforge.net/manual/setup.html for further details. This enables you to play around with MSX Basic and all other features provided by the standard MSX firmware.
Furthermore, if you are a power user, you may want to read the user manual for an overview of the advanced features of openMSX: http://openmsx.org/manual/user.html