I realise that besides my actuarial CT subjects, I've been thinking loads about designing games. Two games in particular come to mind: Fantasy of War (which I'm ill-equipped to build) and new cards for Hecatomb.
While thinking a lot about how to make new Hecatomb cards, I realised what has to be done. A lot of rules clarification. Since like Magic, Hecatomb is all about making cards which push, bend and break the rules of the game. You begin to have to define entire series of problems - every card you make can cause another card you made earlier to malfunction, have unclear consequences, or become downright broken. Every new mechanic has to be defined for just about every situation you can think of - especially for problem cards which in particular mess with this mechanic.
And that's before balancing. This is both the benefit and curse of trying to work with a game that didn't get very far. Just like law - you have to look at the intention when the card was orignally made, not just what the card says. The benefit? You get to define everything that wasn't defined. The curse? You have to define everything that needs to be defined - and that's not always the card with card games, as judges at official events will easily tell you.
On the other hand, I've got an advantage too: I'm starting with both a clean slate and a preset environment. While I don't have a playtesting team, I can errata cards with an update, and it won't be a pain to keep up to date (like with real physical cards where the official wording can occasionally drift very very far from the original). I've also got plenty of TCG playing experience to know how to choose rule text well - not to mention how to push the envelope - and even make new card types.
It doesn't matter to me if no one plays it at the end of the day - I'm not making a business out of it (well, unless server load becomes an issue), what matters is that I tried to make it.