I'm sorry if we haven't been able to immediately respond to any support emails - there are only two of us who look at emails and we've both been having some time off over the holidays. We should have announced this before taking the time off, so my apologies. If it is urgent you can contact me directly at ashleyivo@scirra.com.
We provide a free edition of Construct 2 on both Steam and directly from our site so you can test out the features and see how it works, and make sure it works smoothly. For the vast majority of our customers we understand Construct 2 is pretty stable, but in some circumstances buggy graphics card drivers can cause crashes. There's not much we can do about that since it's the graphics card vendor who has written broken code, not us.
All content on Steam - the entire catalogue of games and apps - are tied to Steam and require Steam to be running for the game or app to run. This is normal for all Steam content and is enforced by Valve. However if you don't use Steam, it's a good reason to buy it directly from us instead of from Steam. Since Valve handle all authentication and payment for games and apps on the Steam store, I'm afraid we also cannot help with any refund requests - they will have to go via Valve.
I'd encourage everyone to try out the Free edition before thinking about making a purchase - that's what it's there for and giving it a try for a few days before buying should hopefully avoid any surprises.
Edit: I'd also add the Steam version is absolutely identical to the one available from our site in terms of features - it's only the licensing that is different and handled via Steam instead of our usual license file. You can also get beta releases with the Steam version as described here: http://steamcommunity.com/app/227240/discussions/0/810923021602340037/