To unlock every cheat and character in "Ultimate Flash Sonic," players need to enter 595313131313131 in the password select screen. This unlocks Jukebox, Moon Gravity and Sonic Run 2, just to name a few. Players are unable to access the cheat option until they have cleared both Act 1 and Act 2.
If players don't want to unlock every cheat, they can enter individual codes instead of using the master unlock code. For example, to unlock Knuckles as a playable character, players need to enter password 115310101010101. Code 115010131010101 unlocks Tails, while code 115013101010101 unlocks Cream.
"Ultimate Flash Sonic" is a fan-made Sonic game that attempts to capture the fun of playing officially licensed Sonic games. Just like in the official games, the goal is to collect rings and avoid running into enemies while traveling at a fast speed. The game is considered one of the better Sonic Flash games because of decent controls and the addition of several characters from the Sonic universe.
The game is played in Internet browsers that support Adobe Flash. The controls are handled via the keyboard, so players move Sonic with the arrow keys and make him jump with the space bar. Players can also do Sonic's spin dash by holding the down arrow and hitting the space bar. The game can paused at any time by hitting the enter key.