The first of the games is Snake, which can be summoned by going to Menu/Fun & Games/Games/ERIX, selecting New Game, choosing any difficulty and typing "123" just as the logo comes up. Then there’s Blocks, which quite similar to Snake can be summoned by going to Menu/Fun & Games/Games/Q, selecting New Game, hitting "1" for Level and typing in "134679
#5" while the Q logo is displayed. Note that on both these games, all button presses must be completed while the logo is still appearing.
In addition to these two larger games, there are also a couple of other goodies hidden in the T68, including a simple Higher/Lower card game that appears if you enter "654456" in the Ripple game logo screen, as well as a little message saying "Live Well" "Be Happy" by entering 397 in the intro screen of Tetris (while the bricks are falling, after starting a new game).