Glue pieces

Glue pieces are kit pieces whose job is to join other pieces: they cover gaps where modules meet at odd angles, hide seams, and make transitions between different kits. The Level Design Book lists "glue" among the common module types, next to floors, walls, doorways and corners (The Level Design Book: Modular kit design).

A kit of only straight walls and 90-degree corners builds boxes. Glue pieces let the same kit build caves, ruins and anything that leaves the grid.

#Glue in a kit

The Level Design Book's gap test for a new kit asks: "do you have enough glue for interior kits with off-angle construction? essential for tunnel or cave kits" (The Level Design Book: Modular kit design). For cave kits it also lists "flanges and arches" and "shells" as module types (The Level Design Book: Modular kit design), which are glue in all but name.

Typical glue pieces, gathered from the examples in Burgess's talk and The Level Design Book (Game Developer: Skyrim's Modular Approach to Level Design; The Level Design Book: Modular kit design; The Level Design Book: Environment Art):

Piece	What it hides or joins
Flange or arch	The gap between two tunnel pieces rotated at different angles
Pillar or column	A vertical seam where two walls meet off-grid
Platform, ledge	A height change between two kits or sub-kits
Rubble, rock, debris	Intersections on the floor or against walls
Transition piece	The join between two different kits, such as a cave and a built corridor

#Bethesda's glue kits

Joel Burgess and Nate Purkeypile's GDC 2013 talk, written up by Burgess, describes the most developed version. In Skyrim's Ratway, hallway pieces were rotated at arbitrary angles to create organic flow, and "there is a gap created between each hallway piece" (Game Developer: Skyrim's Modular Approach to Level Design). The team "covered up this gap using an archway that follows the full curvature of the walls, ceiling and floor" (Game Developer: Skyrim's Modular Approach to Level Design). Burgess calls this the Pivot and Flange system (Game Developer: Skyrim's Modular Approach to Level Design).

Later, Bethesda generalised the idea. Burgess writes that platform kits "are a specific example of what we've started to call 'Glue' kits", which "are essentially made with kit-bashing in mind" and "exist primarily to create transitions between multiple kinds of kits and sub-kits" (Game Developer: Skyrim's Modular Approach to Level Design). Glue becomes a kit of its own, shared across many others. See kitbashing.

Different viewsGlue kits, props, or patch pieces?

Build glue into the kit. Burgess describes dedicated glue kits as the evolution of Bethesda's workflow, designed for joining kits and sub-kits (Game Developer: Skyrim's Modular Approach to Level Design). The Level Design Book's gap test treats enough glue as essential for off-angle kits (The Level Design Book: Modular kit design).

Cover joins with nearby objects. The Level Design Book's environment-art chapter is more casual: arrange modules as well as you can, then hide the join with a nearby object (The Level Design Book: Environment Art). Burgess himself remarks that "no one really notices those little intersections" (Game Developer: Skyrim's Modular Approach to Level Design).

Avoid one-off patch pieces. Burgess warns that one-off "patch pieces" often "subvert the core logic of the kit" (80 Level: Building Huge Open Worlds: Modularity, Kits &…). A reusable glue piece is part of the system; a patch built to fix one spot is not.

In practice: plan a small set of reusable glue pieces with the kit (arches, pillars, a rubble set) and use props for the rest. If you find yourself building a new piece for every awkward join, the kit's grid or pivots probably need rethinking.

modular kits · kitbashing · grids and metrics · set dressing and art passes · showcase (warehouse) map

#Further reading and watching

Skyrim's Modular Approach to Level Design (Game Developer)

Burgess's write-up, including the Ratway flanges and glue kits in "Going off the Grid". Intermediate, free.

ArticleIntermediateFree

Fallout 4's Modular Level Design (GDC 2016)

Burgess and Purkeypile on how Bethesda's kits evolved for an open world. Intermediate, free.

VideoIntermediateFree

The Level Design Book: Modular kit design

the gap test and a list of module types including glue. Beginner, free.

WebBeginnerFree

References

The Level Design Book · Modular kit design · The Level Design Book · web · accessed 2026-10-21

Joel Burgess (co-presented with Nate Purkeypile) · Skyrim's Modular Approach to Level Design · Game Developer (from GDC 2013 Level Design in a Day), 2013 · article · accessed 2026-10-21

The Level Design Book · Environment Art · The Level Design Book · web · accessed 2026-10-21

Joel Burgess (interviewed by Artyom Sergeev) · Building Huge Open Worlds: Modularity, Kits & Art Fatigue · 80 Level, 2018 · article · accessed 2026-10-21

Joel Burgess and Nate Purkeypile (GDC 2016) · Fallout 4's Modular Level Design · YouTube (GDC Festival of Gaming), 2016 · talk · accessed 2026-10-21