GMDX offers new player mechanics, refined AI behavior, reworked weapon mechanics, rebalanced RPG elements, enhanced artistic direction, expanded level design, overhauled audio design, new interactions and simulated effects, improved user interface, and hundreds of bug fixes.
The author claims to stick to the original design principles as closely as possible to achieve the best way to play Deus Ex today. A list of prominent features follows below.
- Variable NPC senses and reactions based on difficulty. On higher difficulties, NPCs are more aggressive about seeking out the player and stay in the alert phase for longer.
- New alarm dynamics – enemies sound the alarm if dead/unconscious allies are spotted.
- Greatly improved NPC pathfinding, hazard avoidance, and tactics.
- Smarter combat behavior, such as shooting destructible cover, laying down suppressive fire, flushing out the player with grenades, and strafing around corners.
- Expanded behaviors for particular enemies – human enemies have a new melee swipe attack, dogs bark when they detect you, elite MJ12 soldiers employ cloaking, and more.
Enhanced Artistic Direction and Level DesignEdit
- New aesthetic details, textures, and effects are applied to levels to update their look and feel while retaining their identity.
- A few levels have expanded areas, including alternate paths that emphasize having certain skills to provide more weight to them (e.g. lockpicking, swimming, environmental training).
- New Vision and HDTP, two major graphics mods, are both bundled and reworked to go along with the visual enhancements.
Audio Design and New EffectsEdit
- New sounds applied to several effects, including activation and deactivation of augmentations.
- New ambient sounds added to levels, such as the sounds of working machinery.
- Music altered in some levels, like Paris' catacombs not playing Paris Streets' track to highlight ambient sound design, and playing an unused theme while leaving the naval shipyards.
- New walk sounds for various surfaces, as well as ladder-climbing sounds and sounds for falling from height.
- Death sounds were updated and made more varied.
- Augmentations, such as Cloaking and Vision Enhancement feature new activation sounds and visual effects.
- Physics system for movable objects was expanded on to make them more dynamic. Examples include barrels spinning while midair, or knives rotating around their axis before landing on the ground.
- The player can mantle ledges, letting them move around the world more freely.
- The player can assign secondary weapons (e.g. grenades) to use in combat with the press of a button.
- The Microfibral Muscle augmentation allows the player to power-throw objects for high damage.
- The scope modification allows GEP rockets to be steered remotely, and the laser mod allows them to be guided directly.
- Holding the left and right lean keys together allows the player to peek over cover.
- A new stamina system determines how long the player can run. It replaces the oxygen meter in the original.
- Objects can be used in the world by left clicking them with nothing in hand.
- There's an upper limit to eating food on Hardcore mode, and if the player eats too much they can no longer consume food until progress has been made till certain points.
- Equippable items now only can occupy one inventory slot, and the charge of ballistic armor and hazmat suits depletes not with use but with damage sustained.
- Overhauled weapon behavior to feature more prominent, realistic recoil and provide weight to combat, while adding value to recoil mods.
- Extensive rebalancing of weapon statistics and attributes, like pistols no longer killing the player with a single headshot on Realistic and the throwing knives doing significantly more damage than in the base game.
- Expanded weapon modding system, with 3 new weapon mods: damage, full-auto, and rate-of-fire. Weapons also accept a greater variety of mods.
- New ammo types such as rubber shotgun pellets, armor-piercing pistol ammo, and taser darts.
- New firing sounds and unique sounds to simulate reloading, dry-firing, etc.
- Melee hitboxes were altered to aid takedowns, and ranges are more forgiving for stealth knockouts.
- Unique weapon behavior, like tranquilizer darts applying an instant knockout effect when hitting enemies in the head and throwing knives being retrievable from NPC bodies.
- Perks added to the skills to expand on the system and provide minor additional benefits to the player. Examples include long-range multitooling, reduced scope sway, short fused grenades, and the ability to neutralize poison with medkits.
- Augmentation design altered, with three different methods of activation depending on the type to make them more convenient to use: active, passive and contextual. Microfibral Muscle for instance is passive; it's essentially always on, only draining energy when heavy objects are thrown. Power Recirculator is contextual, activating/deactivating on its own when the player turns on/off energy draining augs respectively.
- Augmentation effects generally rebalanced to provide value to some augmentations while nerfing a few others; Regeneration heals slower and with less hitpoints restored than in the original, and Energy Shield is now passive, with EMP Shield's effects merged to make it more versatile in its protection.
- Skills rebalanced and effects altered. Swimming is replaced with Athletics, and now raises how much stamina you have. Environmental Training now raises how many wearables can be stacked per slot, in addition to making them last longer. There's also a new skill added, Stealth, which provides several sneaking related benefits, like leaning faster, making less noise during certain actions like mantling or falling, and more.
Tweakable User ExperienceEdit
- Difficulty modes now influence a vast array of variables besides just bullet damage, such as enemy placement, awareness of the player, certain hazards, and resource availability, to accommodate a wider set of difficulties than the original. Easy for instance is more forgiving than the same mode in vanilla, with crosshairs zooming in faster, reduced damage from all sources, and more player tools provided.
- A new Hardcore mode offers additional challenge through new AI behavior (e.g. cameras noticing bodies, NPCs hearing camera alerts), heightened senses and combat behavior, a hunger system, higher lockpick/multitool strengths, and forced checkpoint saving.
- New menu options include real-time inventory, first-person death perspective, autosaving, custom color themes, the ability to reject combat knives when looting enemies, and the ability to disable many of GMDX’s new features: these go with the expanded difficulty modes to provide a more modular approach.
A team called The Maintenance Men, unrelated to the original GMDX developer, sought to further refine the mod. The "GMDX 'v10' Community Edition" was released in December 2018, featuring various tweaks and improvements in gameplay, graphics, sound, stability, and performance. It also removed many assets borrowed from various games and other mods.