Dawn of the Tiberium Age (DTA) is a stand-alone mod that combines Tiberian Dawn (C&C 95) and Red Alert. While classic mode gets as close to the original game-play and balance as possible, Enhanced mode provides improved game balance and a lot of fun new stuff. DTA features many customization options for Skirmish and multiplayer (where you can play as GDI, Nod, Allies and Soviet on over 100 maps), challenging original singleplayer missions, as well as co-op missions. Since this is a stand-alone mod, you don't require anything but the mod itself to be able to play: the original game is not required.
Until now, GDI has only had the Rocket Launcher for bombarding long-range defenses. While it's a great fire-support unit with its versatile combo of relatively fast speed, AA, and great anti-building and anti-infantry damage, its anti-armor damage and range is low compared to other factions' artillery. This had left GDI with trouble breaking past a heavily turtling player's defenses.
To fix this inadequacy, GDI has developed the Disc Launcher. This Tech-Center level artillery uses electromagnetic rails to accelerate a disc-shaped projectile into high rotational speed. This projectile hits the first enemy object on its way, and its high motion energy allows the Disc Launcher to quickly smash even the heaviest armor from a distance. Just make sure that you're targeting something that doesn't move out of the way, as the disc isn't as fast as traditional projectiles and so can be dodged by lighter enemy units.
Disc Launchers are also expensive and fragile, so don't let them get caught in nukes.