Ultimate mode

Ultimate mode is a special difficulty level accessed by typing ultimate on the title screen or running the game with the -ultimatemode command line parameter. When ultimate is typed on the title screen, the "Play without saving" save slot on the Select Game screen is automatically swapped with the "Ultimate mode" slot, which allows the game to be played in Ultimate mode. Typing ultimate again will undo this, restoring the slot to normal. Like the slot it replaces, the game will not be saved during the entire playthrough, so will have to be restarted from the beginning if the player dies. Ultimate mode differs from the normal game in these ways:

• The player starts with one life and no continues.
• All rings and ring monitors are removed, except in Special Stages.
• All shield monitors are removed.
• Extra life monitors will not give extra lives despite still being present in the game. When popped, they will instead play an error sound to indicate that they do nothing.
• All Special Stage Tokens are removed.
• Both types of Jetty-Syns (and any other Objects using A_JetChase) will have doubled speed and fly higher above the target player.
• Both types of Buzzes (and any other objects using A_BuzzFly) will be 1.25 times faster.
• All Objects using the actions A_LobShot, A_FireShot, A_SuperFireShot, A_JetgShoot, A_MultiShot and A_BrakFireShot will have half the usual reaction time set afterwards.

Beating specific levels, or clearing the whole game a specific amount of times, in Ultimate mode can be used as custom unlockable conditions. Beating the game in Ultimate mode does not give any rewards in regular SRB2 however.