Part of the S2engine basic edition licence;

4. FEES.
(a) The S2BE License fee for the Engine is 100 euros per EACH Game made with the engine tools and script sources. There are no additional royalties. Licensee does not have to show the Games or publish the Games with Profenix Studio.
(b) Licensee agrees to display a full screen, unmodified S2Engine logo for no less than four full seconds in the start up sequence of any game created and released with the Engine.
(c) Licensee agrees to include in the "About" box or in the credits screen: (i) a link to www.profenix.com, and (ii) the wording "This game powered by the S2Engine."
(d) Licensor may use Licensee's name in connection with the Games and in any customer reference list or in any press release issued by Licensor regarding the licensing of the Engine.

I like to keep scripting simple, life is hard enough as it is.
Regards,
Frits