SpaceChem is a gem on Steam for programmers and puzzle lovers. So is the 63 Corvi campaign. It was a great sense of accomplishment to beat both the base game and the campaign.
The 63 Corvi campaign stays consistent with the base game's chapters with its mix of research and production assignments (no defense mission this time, just an "execution" type level at the end). The first two of the 7 assignments are easy and then the difficulty spikes up. However, just like in the base game, you do learn tricks as you solve the more difficult puzzles that help you strategize your approach in later and even more difficult assignments.
The new quantum tunnenling puzzle mechanic basically just swaps individual atoms across a barrier in the middle of the reactor. Any atoms that collide with the barrier results in an error so you have less space to work with this time around and any bonds between the swapped atom and other atom(s) are broken. I really felt that this new mechanic made the whole campaign feel unique and not just some uninspired, rehashed addon.
All of the other puzzle mechanics are retained from the base game except flip-flops, fuse commands, and split commands (from researchNet).
A must buy for all those who enjoyed the base game and want more.