I tried the Microsoft Pocketpak version on my phone(the one I was thinking about)....wow, this is not what I thought it was, it ran ok but, a bunch of issues with 6.5.3+ (could not even close it, no X). BTW it was really ugly too back from the PocketPC 2000 days.
I found...
http://teknowmagic.net/othello.html
Looks pretty good and free...
And I tried the Boardgames version again (as I have it when it was a free download and I can't find the free download any more to link it, it's $9.99 on astraware's site), one of the better versions of it....
So, not too many versions of it...but, I'll stick with Astraware's version for now and it's got more if you like the other stuff.