Spoilers ahead: for the puzzle and the movies/games
This post assumes you've already solved the puzzle. It reveals all categories and their connections, and discusses plot details, endings, and spoilers for featured movies/games throughout.
Platypus built its side-scrolling world from modeling clay, photographed it, and turned the results into game art. Its name is literal twice over: the hero is a plane, and nearly everything looks recently pressed by a thumb.
Games: Portal Stories: Mel · Magrunner: Dark Pulse · Q.U.B.E. 2 · Lightmatter
Portal Stories: Mel is a free fan-made campaign built in the Portal 2 engine. It gives Mel a prototype portal device and expects players to remember that Aperture Science never met a test chamber it could not overcomplicate.
Magrunner swaps portals for magnetic polarity, Q.U.B.E. 2 uses colored blocks, and Lightmatter makes shadow lethal. All four hand the player a strange rule, lock the door, and wait for understanding to happen.
Games: Claymates · ClayFighter · Platypus · Claybook
Claymates and ClayFighter came from Interplay's early 1990s clay-animation run. One is a platformer about transformed animals. The other settles disputes by letting clay characters hit each other until the cartridge is satisfied.
Claybook makes the material part of the simulation. Clay deforms, breaks, and flows through each chapter. The world does not merely look handmade. It behaves like somebody left it near a warm lamp.
Games: Iron Brigade · Orcs Must Die! 2 · Dungeon Defenders · Sanctum 2
Iron Brigade began under the name Trenched before a trademark dispute forced a change. Its walking artillery platforms defend fixed positions while the player joins the shooting directly.
That split job defines the group. Orcs Must Die! 2 adds traps and third-person combat, Dungeon Defenders brings action-RPG classes, and Sanctum 2 uses first-person shooting. Build the wall. Become the wall's angriest employee.
Games: Undead Horde 2: Necropolis · The Unliving · Sacrifice · Zombie Night Terror
The individual unit is not the point. The Unliving raises defeated enemies into a growing undead army, while Zombie Night Terror nudges an automatic crowd through mutations and environmental traps.
Sacrifice keeps its wizard on the battlefield as summoned creatures swarm around him. Undead Horde 2 makes rebuilding a necropolis dependent on fresh recruits. The aha is managerial: every hero here has delegated the dangerous work to a crowd with terrible benefits.
ClayFighter remains the day's purest object: a pun developed into an entire fighting game. Today's CineLinkr puzzle also goes miniature, although its tiny people would prefer not to be punched flat.