Shinra Headquarters Invasion
What makes the Shinra Headquarters invasion in Final Fantasy VII so memorable is the flexibility players are allowed to exercise when tackling it. Sure, one could go in and fight tons of Shinra guards, but a quieter, stealthier approach in-line with Metal Gear Solid can also be pulled off. Each route is difficult in its own right, but allowing players the freedom to choose what best suits their playstyle was really quite innovative for the time.
To top it off, infiltrating the place was interesting in that it wasn’t a constant grind to the top. Puzzles and new characters broke up the action, balancing an arc that could have otherwise been a chore to slog through.