Hi there! The demo of Thieves School is available in http://ws.vtrbandaancha.net/En/TS/TS.htm, Downloads section.
It allows to choose one of the two main characters and play 18 levels (9 in Action mode, 9 in Stealth mode). It includes 5 AY tunes.
The TR-DOS full version is in testing phase, and the cassette version viability is being analyzed.