The currency must be purely earnable by playing the game and completing tasks. Gambling is permitted under the condition that it is impossible to purchase the currency used for it. For more information, please see Updating our policy on simulated gambling in the thread Create Experiences for People 17 and Older on Roblox.
The advice in this post is no longer accurate. This contrasts the prior stance to which, as long as there was no Robux involved, it could be passable. As of the same date of this edit, Roblox has officially moved to ban simulated gambling by September 18th, 2023 (in 3 months), which means that all forms of gambling are no longer allowed on the platform.
