Good times though coloured coins weren't an exploit like ordinals. A coloured coin was just a 600 sats tag embedded into the chain and you needed a colour aware wallet to transact them. Moving sats from a coloured address to a normal address would burn the colour tag in the transaction. So technically you'd burn your coloured token if you send it to the wrong wallet.

Those were technically the first NFTs and then the concept never caught on because ETH launched and JPGs (and smart contracts) were moved to ETH. Which was great because Bitcoin's "utility" is currency. That's the only utility we need. But yeah, we also had smart contracts back then already. David Zimbeck wrote the HALO QT client back then. It had a decentralised market and double-deposit escrow and a few other smart contract features. Also never caught on because of ETH making a debut.