I want to add to this with my own experience - I can’t recommend UL personally for this watch, however if you insist on using it, keep the watch faces lightweight and you should be fine. For example - this watch face is a no-go. Vacheron & Constantin Grand Complication 3600 however most should be fine. I’m kind of using that linked one as a reference point.
Playing games has been fine so long as I completely stop the app after I am done using it. I haven’t encountered many issues at all with simple apps like music, GPS, PlayStore itself, and even a remote mouse app I downloaded from the PlayStore, but as everyone is saying above, keep in mind you won’t be able to do any multi-tasking and you’ll need to make sure you close those apps.