Using all your figures at once - well, sort of

Over on the Lead Adventures Forum someone mooted the idea of basing a game in the same universe as the comic Grimjack. I read it back in the eighties and have a complete set of the originals tucked away in the cupboard. I drank this comic up and could not get enough of it. Grimjack is actually set in the city of Cynosure at the centre of all the dimensions. The city actually consists of the intersections of many dimensions. Thus, you can cross the street and the rules of reality will change. Some dimensions are more stable than others, which means that you can be fairly sure of not getting stuck in some of the dimensions, while others might move off and drag you with them if you stay too long.

In some areas of Cynosure magic works but guns don't and vice versa. Occasionally both work together. In some areas people are gods, while they are just ordinary winos when they are in other areas. Worse still, some dimensions are totally inimical to most life forms. Better stay out of those. Still, it does provide plenty of variety.

So, what does this have to do with using all your figures at once? Actually, very little. What it really has to do with is using all of your figures in the same game setting. You see, and most of you will be way ahead of me on this, in a world where all the dimensions eventually meet, any type of figure could find its way there. So, your Conan figure could fight alongside your Space Womble figure in an epic battle to save the multiverse, or just a squalid fight to earn a few Creds and buy more beer. The question, though, is which rules to use. The setting is hard-boiled detective fiction; think Dashiell Hammett and Raymond Chandler. However, it also introduces science fiction and fantasy into the mix. So, the rules need to support the hard-boiled feel of the comic, while also permitting pure fantasy games, pure science fiction games, science fantasy games, the occasional superhero and a god or two. Not much to ask, eh?

My current thinking is that the core rules should be something like 45 Adventures. The narrative approach to the games and their small size would suit the episodic nature of a comic. You also have the other rules by Rattrap Productions, which use the same system and cover different genres: swashbuckling, Conan-esque fantasy and pulp science fiction. With a little work, these cover most of the bases, especially when you add in the Weird War Two and mad science supplements. The only problem I foresee is the need to work up some character archetypes that suit the core setting specifically rather than peripheral dimensions. Another alternative would be GURPS. Although it is a role-playing game, GURPS has at its core a solid skirmish game for its combat system. There are also zillions of supplements covering most genres that you could want. The only problem with that is the sheer expense of getting all the supplements you might want. Similarly, TwoHourWargames has several rules sets that could be combined to fit the setting and their Rep system makes characters easily portable between sets too.

My question to the audience is, what other rules might handle this well and have good flavour? Have any of you done anything like this before? Could this be the future of my skirmish gaming?