A brand new Atari 7800 cartridge will be available next month for $60 and has just been released on Windows via Steam for $10: https://store.steampowered.com/app/893690/Rikki__Vikki/
In my opinion, the most interesting feature of the game is it’s custom audio chip they’re calling the “BupChip”, making this a game that allows the 7800 to output a quality it’s never been able to before. More info on this chip, as well as some of their development tools can be found on the AtariAge thread: http://atariage.com/forums/topic/285896-rikki-vikki/
Main game features Include:
• Six colossal caverns with 100 puzzles to challenge and master.
• High-definition graphics with seven dazzling colors.
• Unique adventures for both one and two players.
• Dynamic difficulty lets you play for story or go for the high score.
• Both foxes and boxes on-screen simultaneously.
• 6 MEGA-POWER of intense inconvenience.
For more information, please check out the main website: http://rikkiandvikki.com