Below is a list of the first MD games to get to XX Meg count in cartridge (well, rom) size.
Like with the SNES, 32 meg (4 MB) was the cart size limit (vs 330 for the Neo-Geo) without using bank-switching mechanism (which gave us the Giga shock experience...), though I'm not sure if there was a minimum size limit (some sites say 4 meg though it cannot be as there are even 1 meg games -Ms Pac-Man, Columns, etc.)
MEGA POWER in ascending order (not by date anymore):
0.25 Game Genie (software) 1992
0.5 Super Ping-Pong (unlicensed) 1991
1 Columns 1990
2 Osomatsu-kun Hachamecha Gekijou (japanese exclusive) 1988
3 Mystic Defender (japanese version) 1989
4 Space Harrier II 1988
5 Ghouls 'n' Ghosts 1989
6 Phantasy Star II 1989
8 Strider 1990
10 Genghis Khan II (japanese version) 1993
12 Star Control 1991
16 Landstalker 1992
20 Panorama Cotton 1994
24 Street Fighter II' 1993
32 Saturday Night Slammasters 1994
40 Super Street Fighter II 1994 *
48 Sonic VR (unlicensed hack) 2011 *
64 Pier Solar (unlicensed) 2010 *
80 (104 with tracks) Ultimate Mortal Kombat Trilogy + Revelations (unlicensed hacks) 2004-2014
80 Paprium (unlicensed) 2020 *
*: uses bank switching technique to stay within the 32 meg limit visible to the system
BOLD: biggest game ever at the time of release (on cart)
UMKT size goes beyond 80 meg if you count the streamed horrible techno tracks included in some builds (they do not fit the game at all). The game doesn't even use a mapper so not playable on real hardware (except for Mega Everdrive x7) nor Fusion (use an emu that plays bigger roms than 6MB).
There were only 18 maximum capacity (32 meg) games released:
College Slam
Duke Nukem 3D
Frank Thomas Big Hurt Baseball
Jurassic Park 2 - The Lost World
Mortal Kombat 3
NFL Quarterback Club 96
Pocahontas
Revolution X
Saturday Night Slam Masters
Sonic 3D Blast
Toughman Contest
Toy Story
Triple Play '96
Triple Play Gold
Ultimate Mortal Kombat 3
Virtua Fighter 2
WWF Wrestlemania Arcade
X-perts
Thoughts?