WebTug Classic guide. The controls, scores, and shared character rules on this page describe Classic. The six science arcade games have their own controls and simplified physics.
WHAT THE GENERATOR CONTROLS
Each new tree opening begins with a candidate vertical center. The generator keeps the full opening inside the arena, compares it with the previous center, and clamps the change to a reachable range that scales with arena height. On portrait screens it also blocks a second severe move in the same vertical direction immediately after a severe move.
The rule does not flatten every sequence. Reversals and large single changes remain, because reading those changes is the central skill. It removes a narrow class of hostile sequences without converting the forest into a repeating lane.
TEST SETUP
I ran the same reachability function used by the game with deterministic seed 20260726. The simulated arena was 700 pixels high in portrait orientation, with the current gap and world-scale values. The script generated 20,000 consecutive transitions and counted moves larger than 65% of the allowed maximum. Separately, after a move above 78% of the maximum, it verified that a same-direction continuation did not exceed 55% of that maximum.
Sample20,000 generated pairs
Arena700 px, portrait
Seed20260726
PRNG32-bit linear congruential generator
Allowed center range138.971–542.029 px
Maximum step146.876 px
stateₙ₊₁ = (1664525 × stateₙ + 1013904223) mod 2³²Divide each unsigned 32-bit state by 2³² to obtain the next value in [0, 1). The published test uses the same chooseReachableGapY implementation and constants as the August 28, 2026 game build.
RESULTS
The largest measured change was 146.876 pixels, matching the configured cap. More than a third of transitions still counted as large under the test threshold, so the constraint is not silently reducing every run to small steps. The zero count applies only to the specific forbidden pattern defined above.
WHAT THIS TEST DOES NOT PROVE
A generator constraint cannot guarantee that every player can recover from every prior mistake. A technically reachable opening may still be difficult if the spider enters the previous opening at a bad height or at maximum downward speed. The test also does not measure perceived difficulty, reaction time, browser frame loss, or every possible screen shape.
Those limits are why generator changes are checked in three ways: automated range tests, seeded long sequences, and real runs on narrow portrait and wider landscape layouts. A suspicious sequence should still be reported with screen orientation and, if possible, a recording.