To me it means games with open-source servers; there's an old zDaemon codebase that was open-source, and Q[1-3] at least are completely open software.
So I'd say, it needs to be UNIX, as the (non-interpreted) open-source game-servers I'm aware of all come in UNIXy variants. Therefore Linux, out of popularity, hence hardware support.

I'm definitely gonna say OMAP3 is the best option this way I've seen; the various x86s all lack efficiency, performance, or both.
I'm inclined to say one full-SD is all it needs built-in if it has appropriate interfaces for expansion.
n would be nice here, to get best range for uplink purposes, but probably g...Probably need to push this offboard.
Including zealous autoconfig, of course.
Do we need slave mode? It doesn't hurt. USB networking or serial for another internet-access channel, and since OMAP35xx all have them, it's cool.
Possible, maybe, but I'm afraid pretty hard for a start-up operation. (Or are you trying to get Nokia to do this? ) I can see going to $400.
Much as I'm tempted to say yes, just HTML, that's not really cross-platform enough. Dual interfaces via tty and HTML, with the tty access possible by USB/BT serial or telnet. Seriously, it's only software, and if content and presentation are properly segregated in design, there's no reason C64s, Newtons, and anything else lacking a modern browser shouldn't be able to hookup for a little fun.
Practically necessary. And miniSD WILL NOT CUT IT!
-1U max size[/quote]What? not 1U of 19" rack, I hope! It should be thinner, anyway.[quote]
Yes, but more than one; USB is our main expansion option.
Hot-swappable implies a built-in battery separate from the main battery. To me, this means a base unit with a small battery (10-15 minutes runtime, maybe an hour) that will be recharged from an external DC source. This external DC source may be either a big (10+ hour) backpack, or a wall-wart/car adapter/etc. To leave charging hardware out of the device, I'd tend to make the wall connector multipole, so it provides power to the device and a separate connection to recharge the battery.
This gets bulky, and there are at least three sane alternatives: 1.8" (whether SSD or HDD), CF/MicroDrives, and USB drives. They should be modular, and you can add any one (or more) of these.

The SD RAID solutions I'm aware of are 2.5" SATA, BTW, so support for them is best accomplished with a 2.5" drive adapter.

Maybe close in some ways, but 3A is a lot of juice. This thing might have the power needed, but it's a little big (thick, mainly), not modular enough, and eats way too much power. IMHO, of course.
All good modular things, but not in the core.
This is a software-only problem, assuming we've got USB ports, and that's how you plan to connect the printer. And the software needed is completely in existence. It should definitely be included.
External screen capability is really important. It won't be used much for control, but if you can get a projector (say, sneak into a unused classroom between classes...), some good live scoreboards can be shown. Again assuming OMAP35xx, we've got a video out interface; it would be foolish not to have a connector.

It looks like USB can work for the modules except the power-pack. The others might need power connections beyond the 5V/500mA that could be properly provided by USB, so that might have to be provided as well, but I hope not.

So I'd say either a Beagleboard or a Gumstix Overo (from what I've seen) for the main board. The main module is almost the footprint of a 3.5" drive, but thinner. Maybe half as thick, if possible. It has connectors all around, and something like 2 or 3 AA worth of battery.

• HDMI (DVI is too big, use a dongle!)
• USB OTG micro-AB (mini-B's not standard, and micro-A cables are starting to exist...)
• USB ports for expansion. Make these full-A, and stackable modules can just have short pigtails to plug here. I'd say 4.
• BT is internal, with built-in antenna.
• WiFi is internal with antenna but has (room for, at least) external antenna connector.
• 1 external and at least 1 (hopefully 2) internal SD. One internal SD might be microSD, e.g. the gumstix board... (It seems from a brief glance this has one microSD and runs one mmc interface to the connector; if that's right, then one is wasted...)
• Audio input/outputs.

A battery module can clip on the bottom or top; I originally considered a battery module on the bottom and other modules on the top, but if pigtail interconnects (rather than PC/104esque passthroughs) are used everything can stack in any order.
Other modules include:[list][*]PCMCIA -- one type III Cardbus slot; with an electromechanical adapter, CompactFlash/MicroDrives. Good for storage, ethernet and exotic comms stuff. (Ethernet might make sense here, if you have an old 10/100 card laying around.) Maybe a thin spyder variant would take Type II cards while stacked anywhere, or a Type III sticking out the top, if it was on the top; it would still stack and function in any postion.[*]USB-only ExpressCard/54 -- this will work with EC/34 or EC/54 cards, for 3G, storage, ethernet, etc. (This is an electro-mechanical adapter + a voltage regulator.)[*]PATA and/or SATA -- 2.5" drive adapter, could also be used (with spacer, or just additional screws? IDK.) for 1.8". Maybe it's worth making one for 1.8" only; that might fit two 1.8" in one (thinner) case.[*]Anything else running off a USB connection could be made into a module. Some of these make more sense than others, naturally; an optical mouse module would be just wierd, while a GPS module would probably make sense.

These modules all have some sort of keyhole tabs (top and bottom on ALL units) to click together rapidly, and grooves in opposing sides to permit tie-wrapping a stack together for semi-permanent mechanical assembly. Modules have no standard height requirement, and should be as thin as possible without (inordinately) compromising functionality. There are no top-only or bottom-only devices (though modules may gain capability in a particular slot), and pigtails should be just long enough for any reasonable stack height (given a maximum of 6 bricks in a stack: core, battery, and 4 peripherals).

Modules need not be standard USB, of course; as the design as written has no speakers, maybe a speaker module with a 1/8" TRS pigtail is in order? As long as the mechanical interface is simple and generic, and users are prepared to deal with the consequences (carefully ordering stacks to avoid running out of pigtail length!), anything goes. If you wanted, for convenience, you could make the wall-wart stackable, too; again, it has click-tabs top and bottom, so it can be added to either end of a stack, bringing it pretty close to cube form, but ready to travel.

Normally, you'd only need the core and battery modules, which would fit in normal pants pockets. With an expresscard module and a 3G adapter (reasonable even if it's accessed by an N9xx, because you don't want one client dealing with all the traffic from all the clients), it might be a tight squeeze, but doable; definitely in a hip pocket, and perhaps pulling it out to sit down. The "full stack" configuration, of course, would vary depending on what you filled it with; a 2.5" HDD-based jukebox with a speaker module would come out taller than one with 4 one-slot MMC readers.

Software elements in next post. Stupid limit...