Moneo, I'm pretty sure you'll enjoy IFs a lot.
They base themselves on interpreting natural language (not completely, but they come near). It is great that you can try whatever you want, not only following a menu of possible actions.
An example of a game in an IF could be:
1.- The computer gives you a description of where you are:
At last you arrived to the house. It looks like a very old, small wooden box full of holes. The only entrance is a rusty iron door. The only window is slammed with two thick logs of wood. The athmosphere is misty, you start feeling cold and your clothes are wet. The night is approaching, and you can hear the wails of the coyotes
2.- At this point, the player feels like coming inside the house so he can protect himself against the cold, the rain and the coyotes (extrange combination

). A simple prompt is offered to the player. "It's your turn":
>>>_
Then the player can try different things:
>>> enter house
Sorry, but the door is in your way!.
>>> open door
You try to pull and push, but the door doesn't open.
>>> examine door
It is firmly locked. And you don't have the key.
>>> examine window
Two thick logs are nailed firmly to the wall, avoiding any intruders to come into.
>>> pull logs
They are firmly nailed. You can't move'em just with your strength
The player can try whatever he wants to do (within some limits, of course, but I've seen very complex adventures!). At the end, he or she thinks about his/her pockets, 'cause he/she remembers that he took a took box from the car some locations ago...:
>>> inventory
You are carrying a heavy toolbox, a wallet and a bottle.
>>> examine toolbox.
It is closed.
>>> open toolbox and examine it.
You open the toolbox.
The toolbox is closed. You find inside a hammer, a tap and a screw.
>>> remove the nails with the hammer
Good idea, but they seem very rusty and don't move
>>> examine bottle
It contains oil from the engine of your car.
>>> use oil in the nails
They seem to be more lubricated now.
>>> remove the nails with the hammer
Done!
>>> remove logs
You remove the logs.
>>> enter house
You enter the house thru' the window
And problem solved! I love this kind of games, they left a lot of room for imagination. A good IF is very well written, so if you enjoy reading this is your kind of games.
My project was making a big IF to play online. A server would carry the game, and every player would connect using a client. The problem is that I don't have enough knowledge about netplay, but I would like to spend some time with this in a near future.