En osaa pelata tuota peliä ...
Yeah, that was not excepted, weird.
It's just because it's beta and not all correct answers have been added yet. Report these instances using the little flag, and all shall be well. I reported it 19 Aug 2020.
En tiedä, kuinka tuota peliä pelataan.
30 August and it still rejects En osaa.
Doesn't this translation mean "i can't play that game"?
Osata is "to know how" but it can also be interpreted as can, if by "I can't" you mean that you lack the know how. If by "I can't" you mean you lack the physical ability to do it, you would use voida as the auxiliary verb, en voi pelata.