I don't know for sure.
Utopian already received a delegation in 2017, which was increased in 2018 and completely canceled in 2019. The delegation for dtube was similar in terms of timing, but was only canceled in 2020.
Steemmonsters was probably introduced in 2018. I haven't found an introductory post yet, but the alpha test phase was in 2018. However, it may well be that the “swings” in the diagrams are dominated by the subsequent phases.

As we know, a game like this has a special appeal. Especially as many users would then also be prepared to put money into the system and not just withdraw it. A game development on Steem would certainly help the ecosystem.
However, it is also clear that this is a feat of strength that cannot be achieved alone. Perhaps you as the Steemit team could put out a kind of call for tenders for this. Call for developers to submit concepts and you support them either with a delegation or by supporting a proposal (SPS). I know there have been bad experiences with this in the past. Maybe this doesn't happen anymore because it mainly resulted from the split. But maybe appropriate conditions/provisions can be made.