Open up XTerminal and type :

sudo gainroot

apt-get install preenv

transfer the relevant game folder within 'applications' folder from ur pre to '/home/user/'

if you only have the ipk file ( similiar to the apk files for android ), unzip with 7-zip and you should have the relevant game folders you need to transfer to your n900.

next open up xterm again and type:
sudo gainroot

preenv

( or if its still open )

cd /home/user/applications/'name of game folder'.

chmod +rwx 'name of the game' (for example, need for speed would be nfsuc)

To create a desktop icon type the added line:

desktopgen appinfo.json

then just select the icon from your normal menu like a native game/app

Note 1 : For NSFU when in car purchase/car select screen, to exit have to tap the return button multiple times like a woodpecker, must be a bug due to multi-touch reqs
Note 2 : Games I've tested

- NFSU ( works perfectly)
- SIMS ( No camera rotation due to lack of multitouch)
- LETS GOLF ( Currently testing, seems fine so far )