Multi Emulator Super System (MESS) is an emulator for various consoles and computer systems, based on the MAME core. It used to be a standalone program (which has since been discontinued), but is now integrated into MAME (which is actively developed). MESS emulates portable and console gaming systems, computer platforms, and calculators. The project strives for accuracy and portability and therefore is not always the fastest emulator for any one particular system. Its accuracy makes it also useful for homebrew game development. As of April 2015 MESS supported 994 unique systems with 2,106 total system variations. However, not all of the systems in MESS are functional; some are marked as non-working or are in development. MESS was first released in 1998 and has been under constant development since. MAME and MESS were once separate applications, but were later developed and released together from a single source repository. MAMEDEV member David Haywood maintained and distributed UME (Universal Machine Emulator) which combined much of the functionality of MAME and MESS in a single application. On May 27, 2015, MESS was formally integrated with MAME and became a part of MAME. License MESS was distributed under the MAME Licence, which allowed for the redistribution of binary files and source code, either modified or unmodified, but disallowed selling MESS or using it commercially. The license is similar to other copyleft licenses in requiring that rights and obligations provided in the license must be remain intact when MESS or derivative works are distributed. In addition to the MESS Licence, The MESS Team required that: "MESS must be distributed only in the original archives. You are not allowed to distribute a modified version, nor to remove and/or add files to the archive. Adding one text file to advertise your web site is tolerated only if your site contributes original material to the emulation scene." The MAME license required source code be included with versions of MESS that are modified from the original source, while the MESS legal page states that when distributing binary files "you should also distribute the source code. If you can't do that, you must provide a pointer to a place where the source can be obtained." While MESS was available in both binary and source code forms, the restrictions on commercial exploitation cause it to fall outside of the Free Software Foundation's definition of free software. Similarly MESS was not considered to