There is supposedly a bug in the CD-ROM version that sometimes causes the program to forget to credit points, so it's possible to finish the game having performed all correct actions and still not have the maximum score.
Xenon: Space Quest XII
On the streets of Xenon, you need to look out for a wandering zombie/cyborg (…which I have never seen). If it gets close to you, it will scream, summoning a security droid. The droid itself is also wandering around. To hide, walk Roger behind a convenient piece of scenery; any will do, as long as no part of Roger is visible on screen. (Fortunately, the timer patches eliminated the impossibility here.)
Go west. Look at the skimmer. Click the hand on it. Open the glovebox and get the Pocket Pal. Go north. Search the tank. Get the unstable ordnance, then replace it in the tank. Return south and then go east twice. Get the yellow piece of rope. Go north. Hide behind the Y-shaped support and click the rope on the ground. Roger will tie a noose and lie in wait for the bunny. Position the hand cursor over the loop and wait. When the bunny crosses the rope, click. Look at the bunny in inventory, then remove its battery. Put the battery in the Pocket Pal. If you haven't already dodged the droid, hang around until it comes on screen (since you're already hidden). You score points for evading it. When finished, open the sewer grate. Take the jar from the table. Lift the blotter. When the expository hologram is finished, open the door on the west wall and walk into the tunnel. Follow the tunnel west and south. You will pass a grate on the wall and a green slime will ooze out and follow Roger. Save the game. Continue south. As soon as you change screens, click the walk icon on the spot where the tunnel joins in from the east. Click the jar on the ooze. Walk a little ways into the eastern tunnel and wait for the slime to pass. (It may take a few tries to successfully get the ooze and not die.) When you have the slime, climb up the ladder. Wait while four Sequel Police climb out of the shuttle and leave the screen. Click the hand on the ground to climb out of the manhole. Walk east. Climb into the open landing gear compartment. When you climb out of the shuttle in the computer bay, go west. Wait while another time pod materializes and a cop climbs out and starts jawing with the other one. While they are not paying attention, climb into the pod. Note down the code on the screen (Xenon). Enter any sequence of six symbols. Nothing will happen. Enter any other different sequence and you will be taken to Estros.
For Your Amusement:
On the first screen, click the tongue on the supercomputer structure seen in the background.
In the room just under the grate, walk to the bottom edge of the screen (so you can't see Roger's feet), then all the way to the left. Next, select the buckazoid from inventory and click it on the very bottom left corner of your screen (such that you see only a quarter-circle).
Estros: Space Quest X
Go west (careful not to fall off the edge) until a shadow passes overhead. Return east and go down the steps to the south. The dactyl will pick you up and drop you in its nest. Wait until it drops a Sequel Policeman as well. Search the man. Escape through the opening on the southeast edge of the nest. You will be apprehended by three Latex Babes. Get into the submarine. Wait while you are strapped into a torture device. Save the game. When the slug attacks, wait until it has opened your restraints. Push the red button. As soon as Roger climbs out of the chair, grab one of the oxygen canisters. The slug will grab you and draw you towards its mouth. Click the canister on the slug's mouth. It retreats with a bit of indigestion, and the Babes decide to take you shopping as a reward.
For Your Amusement:
When in the dactyl's nest, wait for something to streak across the sky and look at it. (This is supposedly Sir Graham being carried by the condor in KQ1. It rather looked to me like King Graham being carried by the eagle in KQ5.)
Talk to, smell and taste the impaled Sequel Policeman.
Galaxy Galleria: Space Quest X
Pick up the ATM card that Zondra dropped. Step onto the bottom right walkway. Get off at the ATM just past the software store. Use the card on the machine. Seems it won't work since you don't look like the person it belongs to. Get back on the moving walkway. Pass Monolith Burger and go to the Big and Tall shop. Talk to the clerk and get outfitted in new pants and boots. Pay the clerk and leave. Walk to the centre island between the walkways, then get on the one which goes back the way you came, and go to Monolith Burger. Talk to the manager twice and accept the job making burgers. (You cannot score full points if you skip the sequence.) This is fairly simple for the first 15 or so, but then the conveyor speeds up significantly. You will be fired after you screw up five burgers. The most you can make at once is 34, but you will probably be fired before then. Go back inside and get the job as many times as necessary so that you have a total of at least 63 buckazoids. When you're finished, get back on the counter-clockwise walkway and get off at the women's clothing store. Talk to the clerk, pay her, and leave. Follow the walkway around to the mall entrance and pick up the cigar stub. Go back to the ATM and put the card in it. Select "Withdraw funds" and then "Clean it out". You now have 2001 more buckazoids. Continue to the women's store and return to the dressing room to change back into your uniform. Go to the software store. Click the hand on the bargain bin. Move the items aside to find the "Space Quest IV Hint Book" at the bottom. Look at it and purchase it. Go to the arcade and walk to the back right corner. A time pod will materialize on the pad at bottom left. One cop will get out and leave the arcade; another will start walking north. Quickly leave the arcade going straight south. Follow the clockwise walkway to the Zero-G Skate entrance in front of Hz So Good (or Radio Shock, as the case may be). Save the game.
For Your Amusement:
Talk to the bouncer outside the software store when the crowd is gathered there.
Smell, taste, and talk to the condiments at Monolith Burger.
Return to the Big and Tall store after changing back into your regular clothes. The guy rummaging around, pulling out a pair of shorts with red polka dots, is Bob Andrews, former Sierra Online programmer.
Look at all the games in the bargain bin at the software store.
Play Ms. Astro Chicken (the game next to the time-pod pad) and look for Cedric (from KQ5).
Talk to the trash can in the arcade.
Go down the stairs. Shooty and Bang-Bang will start shooting at you. This is a fairly difficult sequence (even with timer patches) and it may take you several tries to survive it. You want to go up to the top of the dome, but in my experience you can't go straight up or you'll be hit. Try going left a bit first, then up. Continue across the dome to the left and you will find you're being followed by the cops. Head for the bottom left corner and as soon as you get there, land at the steps and exit the screen immediately. (Click click click click fast fast fast!!) Enter the arcade and get into the time pod. Write down the coordinates shown on the screen (Galleria). In inventory, click the hand on the hint book to read it. Look for the question about being in the "stupid time pod" and reveal its answers. Then click the hand on the gum wad. Punch in the three symbols from the hint book and then the three from the gum wrapper to go to Ulence Flats.
Ulence Flats: Space Quest I
Go south and enter the bar. Try to get the matches and you will find yourself thrown out on your janitorial ass by the local toughs. Knock over the sand bikes. You will emerge from hiding behind Tiny's hut. Save the game. You will have to dodge a biker at least once before getting back in the pod. To do so, wait until the bike is quite close to you, and then click the walk icon to either side of where Roger is standing. If you did it right, he'll perform a roll. Go east and go back into the bar. Take the matches and leave. Go north. Even if you've already dodged a biker, you'll have to do it here as you approach the time pod. Climb in and enter the code for Xenon.
For Your Amusement:
Smell the Droids-B-Us building. (The Two Guys were sued by Toys-R-Us for the parody in SQ1.)
You will materialize in the bay from which you left. Go east two screens. Use the jar of acidic slime on the door lock. Open the door and enter the tunnel. Light the cigar with the matches and the smoke thus produced will reveal three pairs of laser beams. Click on the control panel to the right. You have to enter a number of degrees (in multiples of 12) for each of the rings to rotate them to a vertical position. In the book and another walkthrough it says to enter 156, 024, and 108, but IME this did not produce the desired effect (rings did not always move at all, for instance). I've had to muck around with them a lot. When you get one upright, you can enter 000 to bypass it on further cycles. When you have them all perfectly vertical, exit to the northwest. Walk up to the connection box at the junction of the north and west catwalks and examine it. Pause the game and make a quick sketch of the plug shape. Backtrack to the time pod and enter the code for the Galleria.
You materialize in the arcade again. Go to Hz So Good/Radio Shock. Look at the salesbot. Select "Catalog" and then "Electronic Gadgets". Select "Continue" until you get to Pocket Pal Connector. Purchase this. Select the correct plug shape. Select "Return to top level" and exit the store. In inventory, use the connector on the Pocket Pal. Return to the arcade, get in the pod, and return to Xenon.
For Your Amusement:
Read all the item descriptions in the catalog.
Xenon Yet Again
Go east and northwest through the tunnel to the catwalks. Use the Pocket Pal on the connection box. The grey rectangle on the right represents you, and the blue circle on the left represents a security droid. Click on the power switch to disconnect. Go north, west, and down the left-hand stairway. Watch while a droid passes on the top level. As soon as it leaves the screen, return up the stairway. Go east, south, and west. Plug the Pocket Pal into the connection box in front of the tunnel. Vohaul will gloat about having your son in custody. Turn off the Pocket Pal and go into the tunnel. Read the hint book again, revealing the answers about being "inside the supercomputer". Note down the number code (6965847669). Walk into the programming chamber. Click the droid icon and click it on the toilet. Save the game. Flush the brain icon. Now you no longer have to worry about the security droid, but you're also on a timer before the computer will be formatted, and your son along with it! Click the "close" button (a la Windows - you surely know how to do this!). Leave the room and go east twice, north, west, down, and west to the glass tube elevator. You will be transported to the top level. Go north, east, and north into the glowing tunnel. When Vohaul is done jabbering and you have control of Roger, press the up arrow key to walk up and grapple Vohaul/Roger Jr. After a moment you will be thrown back. Press up again. Repeat three more times. On the fifth time, Roger will throw Vohaul into the beam, paralyzing him. Quickly climb down the ladder and wait a moment while Roger retrieves Roger Jr.'s personality disk. Click the disk on the panel next to the beam. Click "Disk Upload" to put Roger Jr. into the computer and "Beam Upload" to put Vohaul there as well (which means he gets formatted). Click on Roger Jr.'s name and then "Beam Download" to put him back into his own body. Sit back and watch the confusing father-and-son… er… well, it's not really a re-union, now is it? Aw heck. Just watch the movie.
For Your Amusement at various times:
Any time you're in the time pod, enter the first row of symbols followed by the first symbol in the second row as a code.
Also try the following code sequence: