[ISL]

It's a dead end, but it makes the game kind of interesting (I just exclaimed in the office 'I got to SILICON! Now I can rip up the alpha process to iron! Muahahahahahaha! Then I got iron, and the game was over).

If you can just hammer alphas (Helium nuclei), the game is sorta dull.

I think there's still a ton of merit to this basic idea: Playing on a larger board initially full of hydrogen, allowing correct branching of decay products (so you keep getting back hydrogen in random locations), and allowing fission could be a (complicated) lot of fun.