To all with the missing libsdl-ttf2.0 problem:
I had the same problem and after some trying out with the xterm I found out what it was. There is a problem with the libsdl-ttf2.0-0 which is required for the mupen64plus, I assume it uses the same directory which the other wants to use and because of this, it cant install.
So you have to remove the mupen64plus and other packages who use the the libsdl-ttf2.0 before you can remove itself.
for this you can type:
it will say it can't remove it, because other packages need this (like mupen64plus-arm, Ren'py or python-pygame)
remove all these (via apt-get remove <package name> or via app manager).
Then you can do
or
Then you can reinstall python and pygame
Note: This worked for me, I can't tell if it will work for others, and I'm not responsible if these instructions will do something bad.

Hope this helps.