Duality outlined their formal proposal on the Cosmos Hub forum to become a consumer chain of the Hub. Duality is a DEX appchain with a few differences to others we have seen.
The base design of Duality is an orderbook where traders can place various orders like good-til-cancelled, partial fills, and fill-or-kill. LPs on Duality can create any pool type (stableswap, weighted pools, etc) of which Duality then aggregates on top of the orderbook. Duality also allows for “constant-sum” pools which allow LPs to specify prices where their liquidity lies (similar to limit orders) which differs from the constant product pools where orders are filled tick by tick through a curve.
Duality will also be using ABCI++ to enable multiplicity, their design to mitigate censorship in auctions where multiple validators contribute to blocks vs the leader based monopoly seen in PoS blockchains today.
Maybe most notably, Duality will not be launching a token. Instead, they will use ATOM, not just as the governance token, but will send all fees (besides swap fees) to the Cosmos Hub as well. This differs from other consumer chains where the Hub only gets a cut (15-25%) of the fees generated on the chain.
They are also asking for 500k ATOM from the Hub to seed an initial liquidity pool. The forum post is the first step for discussions, later to be formally posted on-chain. Duality is in testnet.