The best Half-Life 2 singleplayer mods pull from other games. Silent Hill, Mission: Impossible, The Stanley Parable, Half-Life 1 and… Super Mario? MobilityMod's Mobility Mod for Half-Life 2 lets you dispose of enemies by bouncing on their heads—just like Nintendo's iconic Italian plumber.
In the same way Pulse Rifle fodder vaporises enemy Combine soldiers, the Mobility Mod makes quick work of baddies by way of head bashing.
A year in the making, creator MobilityMod says they "probably will" release the mod's source code at some point down the line, and that they're also likely to eventually support Episode 1 and 2. Likewise, while it'd be cool, the creator has no plans to incorporate multiplayer—and instead suggests checking out Titanfall 2's "excellent multiplayer".
It's no surprise then, as teased in the above footage, that the Mobility Mod is inspired by Titanfall 2. It allows double-jumps, powerslides, wall-runs, ledge climbing, airboat rockers (similar to the shooter's Acolyte rockets), the ability to 'cook' grenades, and exploding bullets among other things.