Which is intresting. What's saying the game is incompatible? I know google has a really bad habit of lying about this, so i have a very personal interest in resolving this one.
Well for starters I cant even search the game directly in the store cause when a game/app isnt compatible its non existent on the store for that specific device, so then I searched on google chrome and it came up which then directs me to the store page within the play store app and it shows what i've attached.
There's a couple games I have that work like that, too. Found ways to get them working on my system given the engine they run on, and they run just fine. This is definitely an issue with google play's system. There's a couple games i want that i can't get because i could only get them illegally, and there's one that actually cannot run on my tablet but it says it's compatible with my tablet. It's a really annoying setup. I can't tell you the exact reason, but unfortunately you've got the same issue i have. However, Stardew Valley was not doing that for me. Super annoying situation. You might have to contact sony about it, 'cause people who are in the habit of pirating games have contacted google over it and google's saying it's not their problem that they can't buy games legally. So, supposedly, this is Sony's fault in this case, but i don't have much more than that.
Try again now. It was removed as there were reports of compatibility issues with really widescreen phones. Let us know if causes any problems.