First point: I notice that Playroom works fine only on machines where the logged user has administrator rights.
What about a portable version of the game?
Second point: the game requires the Internet connection to be always active, also when playing against bots; would it be possible to implement an alternative game mode, or there's maybe a trick to do with the actual version, so that one can choose whether to play against other human users - so regularly on-line like him/her -, or playing against computer and so not making necessary the Internet connection (especially in case of dial-up 56K) or authentication?
This alternative mode would be useful for a little break during office work or homework, or however for persons not having an Internet connection because too expensive for their budget; this would be optimal both in the installed version but also using a portable version of playroom, so bypassing limits due to proxies and limited user accounts on the machine used.
Hoping these suggestions will be considered and appreciated.

Greetings, by Stefano

For the first point, the playroom is already portable. If you zip all files of the playroom folder and then unzip in another computer in any folder you want, then it works. No DLL is installed in windows directories, so it is perfectly portable.

For the second point, the answer is no. The way the playroom is built prevent from doing any offline version.
All game logic is on the server. In fact your client is stupid, it shows just what the server tell it to show and react to what the server tell him to watch, but doesn't contain any smart game logic. Compare that to your web browser, which only show the webpage and execute javascript according to what the server sent, without knowing anything about the purpose behind.