I think you'll need to use C++ for it. Things like Game Factory and Klik n Play are too limited to make something like that. Game Maker (wich I use) is also not good for something like this. Sure, it's possible, but you can easily get lost in such a big project like this one not to mention that thing like buttons and inputboxes are pain in the behind to make in GM. So, C is your only way.
About that thing that days of one man making a game is over: I belive it's not right. Just check out
GMC and see how many games that one man alone made are released daily. Sure, not a lot of them are really good but they are there. Be sure to check "Staff's choice" forum on GMC for good games that were, mostly, made by one man alone. Also, one member of GMC, hpapilion (I think I spelled it right) acctualy sells GM games and, as far as I know, she really makes some money selling them.
So if you feel like you can do it, go for it!
k: