Orc Problem 6.1: The Four

This is the rarest achievement in the game: 10.8% of players have cleared a level using exactly four turret types with no abilities. Three separate players have published 6.1 layouts for it, and the most useful thing about them is that they disagree.

Why this one is harder than the three-type version

Clearing with three turret types sits at 15.6%; four types sits at 10.8%. More allowance, lower completion rate.

The reason is that the type allowance tracks the level. A one-type run is done on 3.1, a three-type run on 5.1, and the four-type run on 6.1 — and 6.1 has multiple approach routes that all have to be held simultaneously without any abilities to plug a gap. The constraint is not the real difficulty; the map is.

aerouge, whose layout has been read by roughly 2,170 people, notes exactly where it goes wrong: "Most break throughs came from the upper left and right routes."

The grenade-based approach

Most published layouts assume you have unlocked the slow-down grenade branch. With the grenade launcher's 60% slow for 3 seconds and the +30% damage slowed orcs take, a grenade launcher in front of a damage line does a large amount of the work for you.

aerouge's layout uses tesla coils on the corridors, artillery in the upper right, and lasers angled into the corridors. His own suggested refinements are worth reading as a diagnostic of where the layout is thin:

• Move the tesla coil from the lower-left corridor to the upper left
• Fine-tune the teslas at the upper-right entrance
• Get the artillery in the upper right to hit before the laser corridor
• Angle the upper-right lasers more perpendicular, which worked better in the other corridors

That last note matters generally. A commenter on the same guide wrote that they had "totally forgot about lasers bouncing in tight spaces" — with 15 bounces and 550 range, a laser aimed into a narrow corridor hits the column repeatedly instead of once.

The approach without slow-down grenades

Григорий wrote his guide specifically because he could not use anyone else's. In his words, he had upgraded everything except the slow-down grenade branch, every walkthrough he found required those grenades, and so he spent a long time working the level out himself.

His solution replaces the grenade slow with manual ability discipline — which is legal here only if you are not going for the no-ability achievement at the same time. Read his layout as a way to beat 6.1, not as a way to get the four-type achievement:

• Position turrets to avoid committing to the upper part of the map and the lower-right
• Control the bottom-left corner, using the freeze beam sparingly
• Use rockets on orcs that infiltrate
• Pause constantly — he mentions repeatedly pressing space
• Spend air support when orcs accumulate in the bottom-left
• Only when the strafing runs are gone, start using nukes

The ordering there is the transferable part. Strafing runs and nukes are both limited to three per map, so spending the cheaper resource first is what makes the budget last.

What the disagreement tells you

When two layouts for the same level want different things, the useful question is what each one silently assumes about your upgrade tree.

If a layout leans on the grenade launcher's slow, it assumes that branch is unlocked. If it leans on laser corridors, it assumes laser bounce is upgraded enough to matter. If it leans on tesla coils covering the flanks, it assumes their 12-jump chain is developed.

Before copying a layout, check which of those you actually have. That is usually why a "proven" layout collapses on your save.

A practical order of attack

Clear 6.1 normally first, with abilities, using whichever layout matches your upgrade tree. That gets you the Survive 6 achievement at 26.9%.

Only then attempt the four-type, no-ability version. You will know the routes by then, and the achievement becomes a placement puzzle on a map you understand rather than two problems at once.

What we have not documented

We have not reproduced the layout screenshots from either guide — they are the authors' work, and the guides are linked above so you can see them directly. We also do not know which four turret types the achievement counts if you place and then sell a fifth, and no source addresses it.