This post will be filled with spontaneous questions and answers related to whether one should use an existing game engine or create one from scratch.
What budget are you on? If I’m really low on a budget I’ll probably use an engine if it can save me some time we all know; Time is money. The time saving aspect is also present when it comes to maintaining the game and/or improving it. It is important that the engine gives you a good workflow so you can easily work with it. A good idea might be to implement some simple games/demos/ideas in the few engines you are interested of and see which ever suits you the best.
Are you lacking a feature in the engine? You can probably extend the engine if it doesn’t have all the features you require for a game project. Also remember that there are several other engines to choose from which might give you more features for free. This is obviously something you should consider when you make the actual choice.
What platforms should we target? Different engines allow us to target different platforms. This is obviously an important choice to make as well. It is kind of connected to the monetization issue. Do more platforms equal more profit?
So, Anton since you’re into web apps. What about them?