The Experience

Ideally you would create or choose a puzzle via some nice graphical interface. You'd be prompted to install the correct modules in certain places, and do any other physical stuff that's necessary -- it's probably just wire modules that need extra setup.

The installation process should be quick and easy. During the installation process you could be guided by the GUI, and maybe the briefcase too? Eg "put a button module in the illuminated bay". Wire modules can check that wires have been set up correctly by checking for continuity, then feeding back to the GUI.

After modules are installed, they are programmed with whatever they need for the chosen puzzle. Wired programming would be lame, go wireless!

After the briefcase has been set up and programmed, its ready to be played. Grab friends, get ready, start the countdown. Countdown is started via the GUI or a small button on the briefcase?

The briefcase should be freely movable during the game -- no wired power supply or other connections. While playing, the look and feel should be close to the original game -- similar sounds, buttons/switches/whatever, lights, appearance wherever possible.

Winning and losing should be obvious, fun. Some satisfying audio on defusal, appropriate dimming of lights, etc. Losing could be funny -- opportunity to troll people with smoke, firecrackers?

Affect on Design

Given the experience described, certain requirements or goals suggest themselves.

• Need a graphical interface for puzzle selection, installation, programming. Could be on briefcase, but this would likely be small, underpowered, ugly, take up room that modules should be using -- definite no. Could be a PC program, but this limits portability slightly. Ideally then would have a tablet app, which strongly indicates using Bluetooth for connectivity. Still, would probably develop something on PC first, for familiarity and ease of debugging.
• Replaceable and freely movable modules implies modular design (duh), both in terms of mechanical and software design.
• Pluggable modules with exposed bits -- ESD protection!
• Easy and quick installation makes mechanical design important. The original game has up to 11 modules in a briefcase, so even a little time spent on each quickly adds up. A couple of screws per module would be simple design-wise, but seems like that would be slow-ish and fiddly. Maybe a few clips instead? Something clever with magnets? The modules mustn't become disconnected accidentally during the game! Needs much more thought.
• Possible to have multiple of the same kind of module in a briefcase, so modules need some kind of identification/addressing system. Bonus points if you can plug any of those multiples into a slot and have it "become" the correct one, rather than needing to put a specific piece of hardware into a specific place. I.e. for modules of type A, any of the instances A1, A2, or A3 could go into briefcase bay X.
• If we want installation to be guided by the briefcase, it requires some intelligence that is a permanent part of the briefcase.
• Wireless programming and a freely movable briefcase requires batteries.
• The briefcase and modules need to be rugged. They're going to get flipped around, bashed, poked, dropped etc.
• Indicating a win or loss requires a speaker within the briefcase, maybe some extra lights etc.