Difficulty-
1 - hardest, includes FBI guy and scientist
2 - medium, only includes one enemy
3 - easy, no enemies

Controls-
You control E.T. using:
   arrows - walk and run around
   space - raise head to get out of pits
   space - make selections
   space - when walking use space to run

Objective-
Find 3 pieces of a phone in order to call your friends to bring their spaceship to the forest to get you.

Rooms-
You start and end the game in the forest.
Light green rooms with dark green sections (holes)
The Pit (gray with black edges where you fall when walking into a hole)
Home Screen is blue and has Elliot's home at the bottom (where you cannot be caught), FBI (top left) and lab (top right)

Objects-
Candy - a small dot found sometimes in the light green rooms.  Collecting 9 and then calling Elliot will cause him to come collect them and then bring you a piece of the phone

Selectable Icons-
As ET roams the rooms a variety of icons will appear at the top of the screen.  These can be selected by raising his head (hitting space bar)

Call Elliot - a lowercase e with three lines radiating from it
Send enemies home - Roman Numeral 3 (III)
Eat Candy - circle with a dot in it.  Eating candy gives you more energy, extending the time until you get sick
Arrows - warp you to the room in the direction of the arrow
Landing Pad - targe in forest screen where your spaceship will pick you up (hint - find this early in the game!)
Spider thingy - select once you have all three pieces of the phone so that you can call for your spaceship - get to landing area before clock finishes running out.
Question Mark - select this in the green rooms to see a flash where the phone piece is hidden

Other Icons-
The pink phone will appear on the top left - requires three pieces to be complete.
The countdown clock (orange) will appear on the top right - tells you how long from when you call your ship to when it arrives
At the bottom of the screen the single digits to the left are how many pieces of candy you have
At the bottom of the screen the larger number (starts at 9999) is your health

Tips-
Find your landing pad early in the game
The FBI agent steals from you - starting with phone pieces, then moving to candy
The Scientist takes you to the lab - you can fight him by trying to run while he has you (wastes energy)
No one can get you in Elliot's house 

This is actually really simple and nice. I wonder if this simple guide would actually make this game at least playable for me.
Thanks!

I hope it helps - good luck!

NancyKz : You actually played this abomination of a game? well I salute you for doing so and doing a guide on it no less   

Not a bad game guide, simple to read and easy to comprehend, good work here. You walk through everything nicely and it flows nice.

UFC : it's nostalgia - I had it as a kid and loved it.  I know, I know...