CityCoins only exist through mining, which does not begin until 20 independent wallets signal activation after the contract is deployed.
There is no ICO, no pre-sale, and no pre-mine, and there are no CityCoins issued or distributed prior to the start of mining.
Once 20 users register to activate the contract, a 150 block (~24hr) countdown begins, after which anyone is eligible to try and mine the CityCoins within a given Stacks block.
Registration is not required once the contract is activated. After this process is complete, anyone who completes a mining or stacking transaction will automatically be registered as a user.
A nominal transaction fee is required in order to send this transaction, paid in STX, and you can optionally include a memo of up to 50 characters that will be recorded on-chain.