Sorry to hear you've had such a bad time with your laptop since.
I've got a Playbook and have side loaded without issue. As far as I know, the only way to install .bar files is via the DDPB Installer, which I assume you used? You can't install .apk files, as you presumably appreciate.
There is a very helpful forum for the Playbook which has lots of 'experts' who will try to help you - Blackberry PlayBook Forums. There is a section for Android Side Loading too, which may be of considerable help.
Not all .apk's have been converted to the necessary .bar files so it's possible the game/app you want isn't available for the PlayBook.
I hope some/all of this helps you ...