Python 2, 97 95 75 72 71 70 69 64 55 54 52 51 50 bytes

lambda a,b:(60>a+b>-1<a>b/22*b-3)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}

Python 2, 97 95 75 72 71 70 69 64 55 54 52 51 50 48 bytes

lambda a,b:(b-61<~a<a>b/22*b-3)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}

Left part (b-61<~a<a>b/22*b-3) is a validity-check, and right part (19<b-(b<30)>a) is a check for game ended.

Python 2, 97 95 75 72 71 70 69 64 55 54 52 51 bytes

lambda a,b:(a>-1<b<=30>a>b/22*b-3)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}

Python 2, 97 95 75 72 71 70 69 64 55 54 52 51 50 bytes

lambda a,b:(60>a+b>-1<a>b/22*b-3)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}

Python 2, 97 95 75 72 71 70 69 64 55 54 bytes

lambda a,b:(a>-1<b<31>a+1>(b>21)*b-2)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}

Python 2, 97 95 75 72 71 70 69 64 55 54 52 51 bytes

lambda a,b:(a>-1<b<=30>a>b/22*b-3)*~(19<b-(b<30)>a)

Try it online!

Takes input as pre-ordered a,b.

Returns -2, -1, 0 for ended, in play, invalid.

_{-1 byte, thanks to Kevin Cruijssen}