Gekioko PunPun Maru is a homebrew game by MtChocolate, which also has the source code public. The game feels a bit like Mario Bros. but seems to be a bit more difficult.

Changes:

* Fixed bug while pressing pause

http://www.smspower.org/forums/14525-GekiokoPunPunMaru

The Mojon Twins are hitting the public with the release of their new Sega Master System game Moggy Master. It even includes source code!

Int this two player only game it’s your goal in each screen to get each one of your pink friends. Avoid touching the green bushes.

http://www.mojontwins.com/juegos_mojonos/moggy-master/

Haroldo Pinheiro is currently working on a rather interesting project. Just think about having the possibility to compile old Game Boy Developers Kit (GBDK) games on devkitSMS. Basically making Game Boy games alive on the Sega Master System. Just see it as compatibility layer. Follow the development thread to stay updated!

https://github.com/haroldo-ok/sms-gbdk-compat

Christmas Tale for the Sega Master System is a tiny story based Jump’n Run game. Created by pedro76 and Nivarel.

Source: http://www.retroindiegamedevelopers.com/sega-master-system/christmas-tale-v1-00-by-pedro76-nivarel/

http://www.smspower.org/Homebrew/ChristmasTale-SMS

Chappie’s Ears Simon Game is a fancy Simon style game for the Sega Master System by furrtek. Forget colors, ears are in!

Source: http://www.retroindiegamedevelopers.com/sega-master-system/chappies-ears-simon-game-v1-0-by-furrtek/

http://www.smspower.org/Homebrew/ChappiesEarsSimonGame-SMS

Lander 2 by jimiu is a “Lander” style game for the Master System.