Tubes started out as an Atari 7800 game, but got bogged down partly because the 7800 video chip steals too many bus cycles if you display too much data on the screen. Also, I've never been a fan of 6502 code.
The current status is that all Atari 7800 version features have been completely ported over to the Sega Genesis, and a few extra features (like a title screen) added.
AtariAge thread for the 7800 version
AtariAge thread for the Sega Genesis version
|tubes-006.bin.zip||Sega Genesis version 006 - 2009-05-15|
|tubes68-004.bin||Sega Genesis version 004 - 2007-03-06|
|tubes68-003.bin||Sega Genesis version 003 - 2007-02-26|
|tubes68-002.bin||Sega Genesis version 002 - 2007-02-14|
|tubes68-001.bin||Sega Genesis version 001 - 2007-02-05|
|tubes_2005_08_09.zip||Atari 7800 version - 2005-08-09|
|tubes_2005_08_07.zip||Atari 7800 version - 2005-08-07|
|tubes_2005_04_05.zip||Atari 7800 version - 2005-04-05|
|tubes_2004_11_03.zip||Atari 7800 version - 2004-11-03|
|tubes_2004_10_31.zip||Atari 7800 version - 2004-10-31|