What are text-based games and why they are awesome?

Text Quests, Interactive Fiction - what's that?

Well, in my opinion, the simplest way to explain something is to provide an example.

We'll start with Colossal Cave Adventure - if you follow the link, you will be able to play it right now. It was made in 1976. Yeah, this creation is older than many of us. 

Game starts with the text message:

AT THE END OF THE ROAD

You are standing at the end of a road before a small brick building. Around you is a forest. A small stream flows out of the building and down a gully.

Our imagination is already turned on. We already see forest trees that surround us, we hear a sound of water flow. Brick building is near, so maybe it's a good idea to check what is inside? Is it? We type look at the building and the world of the game responds:

It's a small brick building. It seems to be a well house.

Nothing ventured, nothing gained. And we type go inside
(Below you can notice some strings that start with >> - these symbols indicate what we type in-game)

INSIDE BUILDING
You are inside a building, a well house for a large spring.
There are some keys on the ground here.
There is tasty food here.
There is a shiny brass lamp nearby.
There is an empty bottle here.

Here we go, let's take keys

Taken.

>> eat food

(first taking the tasty food)
Delicious!

>> take bottle

Taken.

>> take bottle

Taken.

Well, we are loaded, time to find our way out of this forest. Let's maybe go out?

>> go out

AT THE END OF THE ROAD

Now let's go south.

>> go south

IN A VALLEY
You are in a valley in the forest beside a stream tumbling along a rocky bed.

We want more!

>> go south

AT SLIT IN STREAMBED

At your feet all the water of the stream splashes into a 2-inch slit in the rock. Downstream the streambed is bare rock.

If we choose to go south again, what will be waiting us there? Beautiful nature, strange places? Maybe abandoned fortress? Or some misterious creatures? A man with a knife? Or maybe nothing, then we'll just escape into the sunset...

We type what we want to do and the game responds.

Text-games have an unique property: they utilize power of your imagination and fully rely on that. It's their strength and their weakness. If one has no imagination or just doesn't like reading, text-game has no chances - unlike a graphic-oriented game that can just blow anyone's mind using special effects or beautiful environment. On the other hand - not a single nowadays GPU can overperform human imagination - so, if the author of text-game was talented and you have no allergy to reading, this game is your choice.

I'll discuss other aspects of text-based games soon.