Powerstar solution:

SCORE (you start the game with 32 points)
W, N
GET KEY
GET BOOTS
S, S
GET MATCHES
right,right
START TERMINAL (8 points)
GET PAPER
READ PAPER (8 points)
DROP PAPER
N, E, N
GET RADIO
LOOK RADIO (you notice a battery)
GET BATTERY (8 points)
DROP RADIO
N, E
START ENGINE WITH KEY (8 points)
E, E
STOP ENGINE
LOAD FUEL (8 points)
START ENGINE WITH KEY
W, S, E, E, S, E, S (8 points), S, S
STOP ENGINE
WEAR BOOTS
S, W
GET TORCH
E, right
LIGHT TORCH WITH MATCHES (8 points)
OPEN DOOR WITH TORCH (8 points)
DROP TORCH
DROP MATCHES
W
GET LANTERN
PUT BATTERY IN LANTERN
GET TANK
E, S
DROP TANK
W, S
GET COINS
N, W, right (a message flashes on the telescreen 8 points)
E, N, E
OPEN VENT WITH COINS (8 points)
DROP COINS
LIGHT LANTERN (8 points)
E, S, S (you need the lantern)
W, right
HIT GRATE (8 points)
N
GET PISTOL
E, E (dense steam), E, N, S, left
TURN VALVE (you can see your surroundings. 8 points)
S
GET SUIT
N, W, N, W
SHOOT ROBOT WITH LASER (8 points)
N
GET CARDKEY
S, E, E, N
DROP LANTERN
GET MIRROR
S, W, right
OPEN DOOR WITH CARD (8 points)
N, left
PRESS BUTTON (8 points)
S, S
OPEN DOOR WITH CARD,
S, S, S, S
HOLD MIRROR (8 points)
S, S
PRESS GREEN BUTTON (turn transmitter off)
DROP MIRROR
GET BOMB
S, S, S, W
DROP BOMB
E, left, left
PRESS BUTTON (16 points)
E
GET TANK
WEAR SUIT
right
PRESS BUTTON
N
DROP PISTOL
GET AMULET
N
TAKE OFF SUIT
TAKE OFF BOOTS
START ENGINE WITH KEY
N, W, N, W, N, W, S, W
STOP ENGINE
W, W, S, left
OPEN DOOR WITH CARD
E
READ AMULET (amuzoz. 8 points)
left
TURN KEY
ENTER "UGOTIT" (use Ceasar Cipher +20 on "amuzoz". 8 points).