Dungeons & Dragons' next adventure has rules for a new playable race, although players won't exactly have the option of using it when creating their character. [Minor Spoilers for Icewind Dale: Rime of the Frostmaiden follows.] The new Dungeons & Dragons adventure, Icewind Dale: Rime of the Frostmaiden features "Character Secrets," a new way of adding intrigue and a bit of distrust between party members as they venture through the eternal winter that plagues Icewind Dale. These secrets range from the benign to the dangerous and add potential sidequests, character quirks, or hidden threats to the party. Rime of the Frostmaiden recommends that players each pick a secret at random, in order to better create an atmosphere of suspicion and paranoia that matches the setting of the adventure.
One of these Character Secrets is the Doppleganger secret, which allows a character to imitate an NPC and even other PCs. Doppelgangers are an actual monster in Dungeons & Dragons, and Appendix B of Rime of the Frostmaiden even provides variant traits for playing as a doppelganger character. While doppelgangers don't have any of the racial traits of the creature they are imitating, they do have darkvision, and have the ability to innately cast detect thoughts or polymorph into any humanoid they've seen.
While doppelgangers don't have the ability score traits of other races, their ability to read thoughts and polymorph into just about anyone is incredibly useful for stealth purposes. Of course, dopplegangers are traditionally feared in the Forgotten Realms, and the secret notes that residents of Ten-Towns will almost certainly try to drive away or kill the character if they get out.
While some D&D fans will debate whether the doppelganger rules classify it as a "true" playable race, the fact remains that the new adventure provides players with rules for playing as a doppelganger. Playing a doppelganger in Icewind Dale: Rime of the Frostmaiden largely comes down to chance, or perhaps asking your DM during character creation.
Icewind Dale: Rime of the Frostmaiden comes out on September 15th.