Zandronum is a free open-source advanced multiplayer sourceport capable of running various games such as Doom, Doom II, Final Doom, Heretic, Hexen, and as well as others online. It originated from Skulltag, which was based on ZDoom and its counterpart, GZDoom.
Hard Doom is a replacement/enhancement mod that replaces all monsters in the classic Doom games with versions that are similar in role, but more dangerous. In general, Hard-Doom is geared towards players who want a more difficult, genuine experience, and it has a variety of visual effects that are more subtle and don't block your view of the action. Over the years since its initial release, it has been meticulously balanced and rebalanced, with new features and effects added to make this a great mod to play through the popular megawads with, without changing Doom's flavor or core gameplay.
Changes in v6.3.3:
1. Rebalanced the sonic railgun.
2. Sonic railgun drop chance lowered to 7.5% (from 7.8%).
3. Reduced the amount of blood spawned by 50% (except for gibs).
4. Reworked the Hells Fury's attack sequence and made him attack more often.
5. Cleaned up and updated the melee attack code of Cacos, Demons, and Revenants.
6. Shadow Demons no longer cause infighting with other demon variants.
7. The Sonic Railgun Zombie now has a chance to randomly stop firing after a minimum of 6 shots.
8. Lowered the drop rate for the Grenade Launcher from 50% to 40%.
9. The Quad-Shotgun Zombie now has 6,3 spread on single shots (was 6,6) and 13.4,9 on the quad-shot (was 16.8,10.65).
10. The railgun no longer gives clip ammo on pickup.
11. The railgun no longer alerts enemies when reloading.
Sonic Railgun Balance:
1. 30 ammo given on pickup (down from 45).
2. Alt-fire ammo cost is now 10 (down from 15).
3. 5/10/15 damage per primary shot (down from 10-15).
4. 100-125 damage on Alt-fire (down from 100-150).