Play Abrams as Dharok the Wretched: his real armour, greataxe, Karil's crossbow and OSRS sounds, built from your own Old School RuneScape.
Deadlock's Abrams becomes Dharok the Wretched, the Barrows brother from Old School RuneScape, in his real OSRS armour.
When you press Play, the mashup reads Dharok's items, models, colours, sounds and font from your OSRS install and Abrams' files from your Deadlock install, builds the skin as a Deadlock addon (game/citadel/osrs_dharok), adds it to Deadlock's search paths and starts Deadlock. Nothing from either game is downloaded or shared: everything is made on your PC from your own copies, and it rebuilds only when a game updates.
It's a client-side skin for normal matches: other players see their usual Abrams unless they have the mashup too. Not yet included: OSRS's level-up jingle.
Old School RuneScape © Jagex, Deadlock © Valve; not affiliated with either. Built with ValveResourceFormat, ValvePak, SkiaSharp and other MIT/BSD libraries; OSRS cache format from RuneLite (BSD-2). Full notices ship with the files.