Genre: Game Creation System
Developer: Jawx
Publisher: Mandarin Software

After a brief opening splash graphic, the STOS BASIC interpreter appears. Using a configuration accessory-- more on accessories in a moment-- the editor colors and function key-activated quick bar can be totally customized. The editor makes use of the usual "list-edit-run" development cycle, but with some amazing touches, such as the ability to edit lines directly in the list output! With the "accload" command, fully modular components-- called "accessories"-- can be loaded then accessed via the "Help" button menu. Two of them, the sprite animation and icon editors, easily let anyone access the full sixteen colors of the ST's palette. Graphics can also be fully imported from external applications, such as Degas Elite. In net, games made in STOS are graphically indistinguishable from any commercial C or assembler title-- they just run slower.

STOS can play music and sound effects via high-level "play note"-style commands, true, but the best way to get audio going is via another one of STOS's accessories: a full-on music sequencer! This lets you plug in notes and alter their timing for all four of the PSG's channels in a visual way, then immediately play back the sequence, leading to rapid iteration. Once complete, the accessory will dump the audio "tracks" to what STOS calls a "memory bank"-- which can then be loaded, and a track played from, with just one command. Because of the PSG's intrinsically limited capabilities, even those who know little about music theory can have self-composed soundtracks in their games which aren't miles away from the best commercial projects.

STOS comes with a two hundred and eighty three page book, documenting the insane number of built-in functions and language features. The book is filled with concrete examples, and is extremely well organized and indexed. Drawing, moving, and animating a sprite involves just a few lines of code; collision detection is built in, and can be checked with just one additional command. While the language is wonderful to work in generally, it does not support functions with return values-- albeit it does allow for "gosubs"-- and it annoyingly does not allow for white space. It is a line-numbered language, but has a wonderfully smart "renum" command, rendering that pesky aspect moot. Non-compiled games do run a bit slow, so an efficient core loop is a must-- but with the optional compiler, it's not unreasonable to expect fifty percent increases in performance!

This reviewer has played and used many thousands of different pieces of software in his life, and STOS-- especially when paired with the optional compiler-- is probably in the top five or ten on any platform, from any era, from any category: it's that good. Unlike most game creation systems, there really aren't any limitations with STOS other than performance: in fact, there are several examples of successful big-box retailer games which were written in it, and none of the purchasers were any the wiser. Its only draw-back is that its language features aren't quite as thorough as products such as the "LDW Basic Compiler" or the ever-present "GFA Basic"-- but considering STOS is intended purely for game development, that's a point hardly worth mentioning. All-in-all, as of 2019 STOS is the best game creation system in history, and is a good reason to own an Atari ST all by itself. For the record, this reviewer has also heard good things about this product's Amiga follow-up, "AMOS".