ScummVM different from emulator
Script Creation Utility for Maniac Mansion Virtual Machine (ScummVM) is a set of game engine recreations. Originally designed to play LucasArts adventure games that use the SCUMM system, it also supports a variety of non-SCUMM games by companies like Revolution Software and Adventure Soft. It was originally written by Ludvig Strigeus. Released under the terms of the GNU General Public License, ScummVM is free software.
ScummVM is a re-implementation of the part of the software used to interpret the scripting languages such games used to describe the game world rather than emulating the hardware the games ran on; as such, ScummVM allows the games it supports to be played on platforms other than those for which they were originally released.
The team behind it also add improvements such as bug-fixes and translations and works with commercial companies such as GOG.com about re-releases.Features
ScummVM is a program that supports numerous adventure game engines via virtual machines, allowing the user to play supported adventure games on their platform of choice. ScummVM provides none of the original assets for the games it supports, and expects the user to properly own the original game's media so as to use the software legally. The official project website offers games that are freeware that work directly with ScummVM. Atop reimplementing the game executables in portable form, ScummVM enables players to save and load the state of the game at any time, enabling a save system atop whatever the reimplemented game may provide. It has also begun to work at providing alternate controls for newer devices, such as mobile devices with touch screens, which work atop the original games.While ScummVM appears to function equivalently as a game emulator, the ScummVM team does not consider it as such. Outside of some subsystems like audio engines which they are forced to rely on emulation, ScummVM recreates game engines from older languages into more portable C++ code, so that the high-level opcodes in a game's assets will execute in the same manner as their original release, while improving the portability of ScummVM to numerous platforms. The ScummVM team consider this an improvement over simply running the older games and their executables through an operating system emulator, such as DOSBox, since ScummVM's implements are more lightweight and require less processing power and memory, allowing use on more limited processing environments like mobile devices.ResidualVM
ResidualVM (formerly Residual) was a cross-platform computer program comprising 3D game engine recreations with a common graphical user interface. It supports Grim Fandango, Myst III: Exile, and The Longest Journey. It merged with ScummVM in October 2020.ResidualVM was originally designed to play LucasArts adventure games that use the GrimE game engine, and was later adapted to support other ones. Like ScummVM, the VM in ResidualVM stood for virtual machine.ResidualVM is a reimplementation of the part of the software used to interpret the scripting languages by conducting reverse engineering on the original game rather than emulating the hardware on which the games ran.  As such, ResidualVM allows the games it supports to be played on platforms other than those for which they were originally released.
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