Intercept Line-Of-Sight tutorial

The rules for Line-Of-Sight (LOS) are important in Intercept as they govern when you can be seen and when you cannot. In this post I’ll do a step by step that deals with planet LOS, aft centerline and the sun direction. I will cover these in detail but I won’t bother with any actual sensor signatures, scan radius etc. The basic assumption here is that your ship is undetectable when drifting and automatically spotted when thrusting unless you happen to be on the enemies aft arc (as the enemy will always be drifting he should in reality be able to trace LOS through his aft centerline), on his sun direction row or have the LOS blocked by the planet.

Situational report

Well, you are the commander of a UFO that has just finished its mission on earth (anal probing, crop circling, abductions, the usual boring mission) and now it is time for you to exit the solar system undetected. Galactic law allows meddling in human affairs as long as you are never spotted by astronauts, astronomers and similar creatures and the problem is that the humans have put up a space station, known to them as ISS, that is filled with just such beings. If your UFO get spotted the galactics will revoke your license and your Emperor will be most unhappy. Luckily enough your UFO is equipped with a stealth device that make it invisible to all sensors when it is not thrusting. When it thrusts though, all that pent-up heat is radiated away and makes your UFO easily detectable even with the puny telescopes of the ISS station.

You will start your mission in the same orbit as the IIS but on the other side of the planet. You are then to cleverly thrust away from Earth until you leave the map area and can engage your warp drive. In Intercept terms you will have a 1G ship with unlimited endurance that can only thrust when the LOS between you and ISS is blocked from Earth, the sun direction or the ISS rear centerline (the ISS should be able to scan the aft centerline as it is never thrusting but the silly humans put their urine and feces ejection system to eject in the aft centerline so no one will use telescopes in that direction, out of modesty.

Your UFO is currently 1,0 facing SW and the ISS is in -1,0 facing NE. Your gravity assisted drift will take you to 0,-1 and the ISS will drift t 0,1. You decide to turn your ship three steps right so it will face towards S and you will then thrust 1G so your destination will be 0,-2 facing S. After movement is taken care of we must should look and see if the ISS can see us. It is fairly obvious that the LOS is blocked from the planet but let’s see what the Intercept rules actually say about planet LOS.

Centerline blocks entire opposite arc.
Left half arc blocks opposite right halfarc and opposite centerline.
Right half arc blocks opposite left halfarc and opposite centerline.

ISS is on the N centerline which means LOS is blocked to the entire S arc (and vice versa as we are on the centerline too). Incidentally, we are now in Earth’s shadow our Visual(Hull) sig would be reduced by -6. OK so far so good, let’s see what happens next turn. Drift and gravity will take the ISS to 1,1 and our UFO will have its drift at -1,-3 facing S before we apply thrust. We decide to thrust directly to east to get inside the SW arc.

The ISS is on the NE centerline so the entire SW arc should be blocked because Centerline blocks entire opposite arc. We are in the right SW half arc so the NE centerline should be blocked because Right half arc blocks opposite left halfarc and opposite centerline. Can we keep thrusting with blocked LOS or do we have to drift for the next turn? (keep in mind that our UFO is entirely invisible, very much unlike TOS Romulans whose cloaking device only cloaked vision so the clever mr Kirk could still shoot using his sensors). The ISS will be in the W arc so we’ll do our best to get into the E arc and thanks to gravity we are able to do just that.

As you can see from the image, without gravity our drift would be at the x position and our puny 1G acceleration would never get us into the W arc, thank you mr Newton! ISS is on the E centerline so the entire W arc is blocked, and vice versa. So far so good. In the next turn the ISS will move into the S arc and there is no way that we will be able to get into the N arc with our 1G thrust so we will drift for a couple a couple of turns instead. Note that the Intercept rules dictate that Gravity range = Surface gravity x 6 so the gravity well around Earth is 6 squares, beyond which there is no gravity.

We will not be in an opposite arc of the ISS so let’s drift some more shall we.

When the ISS is in the W arc we should finally be able to do some thrusting to finally break free of Earth’s gravitational hold.

The ISS is finally in the W arc so whatever we do inside the E arc will be our little secret. We turn our UFO around 4 steps and thrust 1G to 7,-3. You should know by now that when the ISS is on an arc centerline the entire opposite arc is blocked for LOS, we just barely made it still inside the E arc. The captain aboard the UFO pats his pilot on the back, careful not to disturb his dflrghm.

We are now free of Earth’s gravity pull and can just coast all the way off the map where we can engage our warp drive and the pilot can finally jkhdga his dflrghm. Here’s a shot of our UFO three turns from moving off the map, notice how our trajectory no longer curves when drifting as we are no longer subject to gravity.

The entire escape off the map took 17 turns or 4 hours and 15 minutes to use Earth time units. When the UFO got back their homesystem the Emperor was much pleased with the anal probings, crop circlings and abductions, the crew were to keep their heads this time too. During the following photosession a young alien reporter went up to the celebrities and ask them why it took 17 geflerms (4 hours 15 minutes) to escape the planet. The pilot just started to answer when the commander hushed him and said: “Well, because it is impossible to do it faster without becoming detected by the primitives in their space station”

Can YOU do better? Send an e-mail with a turn by turn account for how you would fly the UFO without detection giving the same starting positions and vectors as outlined above. Remember that ISS aft centerline and ISS sun direction also block LOS in this scenario. Write your solution to (replace the fnord with your favourite cinnamon-bun like character). There may be a price!

May your dflrghm be jkhdga, always!

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