AGIWiki/How to make your game more interesting
Good story is important
First of all, if you dont have a great premise or idea behind your game, you need a good story. Without that there's no point of moving further with your project, unless you are making a game to show some new and interesting features to others. If you have a story then try to transform it into an AGI game walkthrough: that is useful so you can see which of your ideas can be done and which not (because AGI's possibilities ARE limited).
More action, people!
The one who plays your game looks for action, so try to make it possible for ego to communicate with other objects, persons etc. Secondly, it's always good if ego can do as much and take as much as possible. So try to make your ego to climb walls, swim or fly - whatever, it just makes the game more interesting. And there comes the rule - if you've drawn something onto your picture (or if it's a view you've added) ego should (not to say must) be able to "communicate" with it if he can't collect it.
Put more effort into designing rooms
I think that when people are drawing rooms they forget how small basic ego is (36x7) so they draw huge doors for huge houses. That sucks really. In my opinion rooms should better be small than big. Also, it isn't good to use huge walking areas. Because nothing is worse than plain walking. What I mean is - calculate pixels and proportions.
Colours - try not to cover big fields with just one colour, even if it's so in real life or what so ever. Make some shadows, cracks, stains - everything, just to make it more versatile.
Usually there's not much animations in average fan-made game. And the reason is simple - it needs time and patience to make (good) animation. But you can't make good game without time, patience and animations!
And last, but not least - Sound
Sound helps the one who plays the game to bring out his\her emotions. And by doing this, it makes your game more interesting, as simple as that!