I could even create more detailed version how we are here, not there. Especially I developed first apps using engine, years ago.
I think we all already know that splinterlands way for communication with api/database by blockchain is kinda non sense, doesn't really need blockchain. External communication by internal communication. Devs more likely will avoid this route. Works for splinterlands cause made years ago(was it made this way for stats? we don't know, not really important at this point).
Going back to engine and "second" wave of games, developed on engine. Most of them operate on internal engine tx, like transfer of token as game action. Dappradar doesn't track stuff inside engine. They can only say it's unverified engine tx(actually they don't know it's unverified). So game activity is hidden in engine transactions(if you play dcity, most of the actions are transfer of tokens)