In SRB2, a skin is a form of sprite replacement for players, and sometimes other types of Objects in the game. For the player, each skin added to the game creates a playable character whom they can select and play as. Unlike in most Doom ports, skins in SRB2 will not only replace sprites and sounds but will also determine a character's abilities, movement speeds and other statistics, fundamentally defining how they play the game.
Note that the sprite replacement function of skins only applies to sprites belonging to the
SPR_PLAY sprite set, which by default display Sonic in SRB2; when selected by an Object displaying any sprites from this set, skins other than Sonic's skin will automatically replace the default Sonic sprites with those belonging to a different character, transforming the Object's appearance. Apart from the player themselves, the Extra Life Monitor and Level End Sign also make use of this ability to change the icons displayed on them depending on the player's chosen character.
Three characters are available to play as in SRB2 by default – Sonic, Tails and Knuckles. Custom characters can be created and loaded into SRB2 through WAD files for alternative appearances or gameplay – a maximum of 32 skins (and therefore 32 characters) can be loaded into SRB2 in total, including SRB2's default three. To create a skin for a custom character, see the Character creation tutorial.
When starting a new game in Single Player, the character select screen is used to choose the player's character; once this is done, the player normally cannot change characters again afterwards – exceptions to this include going to levels that force the player to use a specific character (using the
ForceCharacter parameter), using the
SKIN console command while development mode is activated, or using Lua scripts to directly modify the skin the player is using. Note that custom characters can optionally choose not to be selectable at the character select screen.
In contrast to Single Player, all characters loaded in SRB2 will automatically be available for use in multiplayer, and the player can switch between them using the
SKIN console command or the Setup Player menu (Multiplayer → Setup Player 1/2) whenever they are idle. However, further restrictions may be applied to players attempting to change characters mid-game, depending on the gametype:
- Co-op: the player's character can be changed at any time whenever the player is idle.
- Race/Competition: the player's character can only be changed during the initial countdown or whenever the player is dead.
- Match/Capture the Flag: the player's character can only be changed when the player is dead or spectating.
- Tag/Hide & Seek: the player's character can be changed freely if the player is currently IT; otherwise, it can only be changed during the hiding time countdown or whenever the player is dead or spectating.
If the console variable
RESTRICTSKINCHANGE is turned off, all the above restrictions besides the player being idle will no longer apply.
S_SKIN is a special text lump that defines the stats for a character in SRB2. The exact name for this lump in a WAD file is partially flexible – SRB2 will recognise any lump with the prefix "S_SKIN" in its lump name as an
S_SKIN lump. For instance, "S_SKIN", "S_SKIN1", "S_SKIN2", "S_SKIN1A", "S_SKINAB" are all acceptable lump names for the
The Character Select (or "Choose Player") screen is where the character to start a new Single Player game with is chosen. By default, there are only four options to choose from: Sonic, Tails, Knuckles, and Sonic & Tails; the last of which starts the game with Sonic but adds a bot as a secondary player playing as Tails, similarly to Sonic 2 and Sonic 3.
Custom character select entries can be created via SOC, which will be displayed at this screen if they are enabled.
- No Sonic: Prevents a linedef action from having an effect when playing as a character with the thok ability.
- No Tails: Prevents a linedef action from having an effect when playing as a character with the fly ability.
- No Knuckles: Prevents a linedef action from having an effect when playing as a character with the glide/climb ability.
None of the above flags on their own will have any effect in multiplayer. If all three are combined, they will prevent a linedef action from having an effect except during multiplayer games.
In versions of SRB2 pre-dating Version 2.1, three emblems were hidden in every non-boss act for Sonic, Tails and Knuckles separately – these type of emblems are collectable only by their associated characters; for all other characters, they will still appear in the map but will be uncollectable (and will display translucent to the player). For details on creating character-specific emblems for SRB2, see Custom unlockables and emblems > Map-specific emblems.