Starknet launched a stack for building appchains.

The solution has been developed since 2020 and has already been used by projects such as Sorare, dYdX, and ImmutableX. SN Stack is available in three versions: StarkWare Sequencer for high-performance dapps, open-source Madara, and Dojo for on-chain games. 

All versions include key components of the Starknet ecosystem, such as CairoVM and Blockifier. The developers emphasize that SN Stack provides scalability, security, and cost efficiency for unique use cases.