Using the promotion sytem..

[Dark_Wizard]

Create a new usergroup call "Arcade Users", then go to "Usergroup Manager" and select "Promotions" then select "Add New Promotion" then do the following:

• * Usergroup: Select the usergroup from the dropdown you want to control (i.e. Registered and make sure this group cannot use the arcade).
  * Posts: Set this to the amount of posts needed to use the arcade.
  * Promotion Strategy: Select Posts
  * Promotion Type: Additional Usergroups
  * Move User to Usergroup: Select Arcade Users
  * Click "Save"

Then go to the "Arcade Users" usergroup and set the arcade permissions.

Your done....