I also work with GameStudio, mainly modelling. In my opinion A6 is a good and solid engine and includes an entire game development suite. It is not the among the most advanced engines on the market, but that is compensated by an easy scripting language and tons of template scripts for almost everything that can be done with it. When i mentioned a complete suite i meant:
- a model editor (that is very weak, but serves to import and convert models properly to the A6 MDL format.
- a level editor (looks and works very similar to Hammer for HL and its actually very good)
- the level editor also serves as a compiler to publish the game .exe
- a script editor (decent, nothing special here)
There are various price configurations, i own the commercial version ($200), which is good, only thing they want is to display the A6 logo for a second at the beginning of the game. For more serious developers there is the Pro version for $1000, but in my opinion its not worth it (the added features are not that relevant).
Game Studio features a physics engine that isn't very good, but is 100% compatible with the freeware
newton physics engine.
Game Studio is oriented towards FPS shooter and action-adventure games, but people have made all sorts of games with it.
And YES adventure games can be done with it as proved by the excellent game Adventure in PociaAnd here are some random shots of games made with A6.
At the moment i'm in a team thats working on this game Byiu Biyu Rocket, a zelda-like adventure RPG.
Hope that info helps.