To give a more consistent damage output for all aim skill levels as well as bringing more viability to auto/semi-auto firearms.
Other notable changes:
SLAMs only give 1 ammo per pick-up rather than 3. Initial reserve ammo for all guns, with the exception of the 357, has been increased by 1 clip and the SMG receiving 2 clips.
The AR2's orb aim assist has been nerfed; the search radius has been halved and guidance reduced by about a third.
Superchargers can still charge you to 200 armor, but they only have 150 stored, so you'll need to collect 50 batteries first if you want the max.
Prop mass and passthrough properties are standardized across all maps, making smaller one's less of a tripping hazard and giving a more consistent experience.
For speeds under 450, there is now a short window to assist with bhop timing to help folks using the space bar or with higher ping/latency.
Gravity (such as for killbox) & air acceleration (such as for surf) are changed per map to provide the intended experience of the creator.
The jump and surf maps have checkpoints (!cp) that are stored per player per map as well as !bring & !goto commands.
Robust anti-cheat and fixes in place, if you believe you've triggered a false positive or a bug, please report it on the hl2dm.community Discord.