@Boule010,

wgames and preenv are in extras-devel. Are you sure you have activated that repository?

Go to the terminal and type:
$ cat /etc/apt/sources.list.d/hildon-application-manager.list

you should see a line containing
deb http://respository.maemo.org/extras-devel/ fremantle free non-free

If not there (or commented out by starting with "#") then add it (or remove the "#").

Then, as root, do "apt-get update" and then "apt-get install wgames"