@Cuantas Vacas commented Yooval Mann's '7-step' method for that game in a recent post, hopefully this link works - https://www.tonegym.co/space/talk?id=NASZ2448MAR&t=87PWJ8MZ3RI
check it out and see if it helps :)

I still suck at this game too btw, another thing that helped me is using the 'Compare' button (clicking c on desktop) and listening to the arpeggiated forms of the inversions to help pick out the intervals
ex. Major triad
root: M3, m3
1st: m3 on bottom
2nd: P4 on bottom

hope some of this is helpful, you (and I lol) are not alone with struggling on this game so hang in there :)

This has gone from being one of my worst to favourite games. Don't be afraid to have your guitar/keyboard etc with you when you play to sound out the chords. Take your time and listen carefully. This has also helped my not only to hear the difference in the inversions but great practice for finding the chords on my guitar as well. Stick with it it's worth it

If you sing at all, try humming each note in the chord after you hear it. If you ever hear that one of the notes is an octave or a P8 then chances are that it is an inversion. If you are using an instrument, practice your inversions on every scale before playing the game to warm up.