The second expansion disc for Red Alert 1 does a lot better job on actually expanding on the game. The biggest difference here is this disc not only gives us new missions and multiplayer maps but also a slew of new units that can be retroactively used in all multiplayer maps from the original game.
New Allied units include a field mechanic, teleporting Chronotanks (which are actually pretty deadly but suffer from the fact that you can't teleport them in groups,) and the nuke carrying Demolition truck (which oddly makes an appearance in RA2 as a Soviet unit.) New Soviet units include a missile sub (equivalent to the Allied Crusier,) Shocking Tesla tanks and Tesla troops (both to reappear in RA2,) and the M.A.D. tank, or Mutually Assured Destruction tank, which causes a small earthquake when it self destructs. The new units add a lot to the strategy of the game, now you can do things like take out an advancing tank collum with shock troops, invade past base defenses with Chronotanks, or send a M.A.D. into the heart of a base while protected with the Iron Curtian. There are other more subtle changes with regular units and buildings as well that may not be so apparent. For instance building two war factories no longer speeds up production of vehicles (which was done to limit multiplayer tank rushes) while the allied turrent defense has a faster rate of fire.
The game includes a campgain of 18 new missions as well as another 100 multiplayer maps. Like the other expansion disc there are no new FMV sequences for these missions, each one is preceeded by a short text only briefing. Most of them involve using the new units in one way or another.
A much better followup to the disappointing Counterstrike that all Red Alert 1 fans should seek out. If you bought the Command & Conquer: The First Decade pack then you own it already.