warning: listening to this could be damaging to your health

Originally Posted by Schroeder

If a S is followed by a T or a P the S is pronounced like a Sch.
Examples:
Sturm -> pronounced Schturm
Spiel -> pronounced Schpiel.

If the S is followed by any other letter it remains a S.

Isch instead of Ich is what a lot of foreigners say who don't have German as their motherlanguage. I'm not aware of a regional German dialect that would pronounce ich like isch (although I think people who speak Swabian might do that....but I'm not sure...).

@Skybird also.
Thank you for the valuable clarifications.

German is even more complex than english. Especialy the grammer. (Rocket science!)
However, it does seem to have the most perfect match between written and spoken.
While danish leaves enough room for spelling errors based on pronunciation, english is a disaster.