We've gotten a couple of really nice looking Switch games so far, but it's future titles that will really show what the hardware can do.
As a more demanding game than Doom, the upcoming Wolfenstein II port should test the Switch's mettle; it will likely have a low resolution and framerate like Doom did, but just getting it to run in a recognizable state is something you just wouldn't have seen on PS3 or 360.
Bayonetta 3 and Metroid Prime 4 could also be potential showcases, same with whatever Shin'en are currently working on.








