I have always been a fan of the game Heroes of Might and Magic 3 (let's call it simply HOMM3), which shined long ago, around 1998.
For more information, this game was created by the 3DO company - which sadly went bankrupt in 2003. Then in 2015, somehow it was 'revived' (a rendition, actually) as HOM3-HD edition by Ubisoft.
Now, I'm thinking of my own game that uses the theme from this game (well, at least use the game characters and audio for example), which might be published onto Google Play and/or App store.
So I'm wondering: would there be any issues (e.g. risks of being sued, for example by Ubisoft) if I try to use HOMM3 (the original one, as I called it above) art and audio ? For audio, I still own a copy of HOMM3 so I have access to the audio (MP3) files directly from the game folder. For arts, there are spritesheets like this: spriters-resource, which seem to be freely available to use.
These are two versions (owned by 3DO vs owned by Ubisoft), but things could get complicated if we are not prepared, so better be safe than sorry.