Forget laser tag, go airsoft. It looks MUCH better, and it has a more realistic feel to it. On the downside, to have a proper game you need people you can trust and will call their hits.

You can get the name brand airsoft guns( Classic Army, ICS, Tokyo Mauri, G&G, etc) for $200-300 while you can get guns from UTG for less than $100 which are almost as good as brand name ones. Also, tactical gear such as vests/helmets/ammo pouches/gun holsters/etc are $50 or less. And sidearms( pistols/Uzis) are on the average only $100( for full steel/blowback).

If you're willing to take a look at airsoft, PM me and i'll tell you everything you need to know.

Forget about 'high intensity conflict simulation': what you and your friend need to do is enlist in the US Army and get shipped to Iraq. There you'll experience combat and maneuvering in authentic desert and urban settings. You'll play tag with snipers, suicide-bombers, and fanatics with machine guns, as well as fend off punk kids who like to throw rocks at soldiers. Its really pretty cool (but like all things in the military, the novelty wears off pretty quickly...)

...sorry, just couldn't resist. Seriously though, this may in fact be a poor time to enlist in the US military?

[EDIT] Hey, I might actually have something useful to contribute here! I think what you want to look into are micros. You can get an 8-bit micro and program it using C, just like a 'normal' computer. A micro is a small rectangular computer, you often see them embedded in circuit boards. About the size of an eraser, or smaller.

I used an Atmel 8-bit micro for my real-time systems course, they're awesome. Be sure to get one with at least two timers, and an ADC (analog to digital converter). This will let you accept inputs from your IR sensors and convert it to an integer value. A DAC (Digital-to-Analog Converter) might be a nice feature if you want to produce analog outputs (like a modem). Otherwise the standard ability to turn pins on and off will probably be good enough.

It seems very easy because you can just upload your C programs into the micro, but figuring out how to use all the features can be very tricky. Expect to read from the micro's manual for three days, and then be able to program the micro to do what you want in about 15 minutes.

But alas, there was nothing precise or accurate about the IR emitters I worked with. All I can say is, don't get the cheapo ones that work like a flashlight. They're awful for wireless communications.

[EDIT 2] Here's a link to Atmel's selection of fine micros The one I used was the ATmega16. You can learn everything you need to know about programming each micro by reading it's data sheet.

Heh, good one.

I think I've got a better idea of this stuff now. The microcontroller has the CPU, memory, and whatnot, but it is not a demo board like I thought it was. I need to buy demo boards, and plug the microcontroller into it. The board would provide easy connectors for all the inputs/outputs, easy way to plug in power, serial port, etc, etc.
Only problem is all the demo boards I've found are $60+. The controller itself is cheap, but these boards are expensive
Can I get a demo board that just lets me plug in a battery, and easily plug in my components (buttons, sensors, emitters, etc) and that's it? Then I could buy the programmer seperately, right? Because I only need one programmer for all the chips.

I've been browsing Sparkfun for a little bit.

So let's say I get:
This PIC
This programmer
and this breadboard

Is that all okay stuff? I seriously have no idea what I'm doing The breadboard comes with jumpers...I guess that's good. I checked to make sure the microcontroller matched with the programmer. One question though, the programmer has a weird cable on it. What is it for? Will I need it, or can I just plug it right in through that COM port thing?

And of course I'm still missing stuff. How do I power the controller? I'd like to hook it up to a battery. I guess I'll need some components for the breadboard and whatnot.

And do I need an oscillator? If so, which should I get?

Am I missing anything else to get the microcontroller running? Once I have everything that'll make it run then I'll start hunting for the other parts.

The micro has 18 pins, but how many of those can I actually use to hook up to stuff? An LCD screen takes a lot of pins, for example, so I want to be sure I have enough.

Note that I have never soldered, nor know how to.

Oh, and how sturdy will the connections to the breadboard be? I assume they'll be pretty weak. In the future, after testing, what will I do to package this up? I can't solder, so that's no good unless I learn. I've read a little bit about a sort of wire wrapping? Does that have any relevance?

Now, something I've learned, AVRs give you much more bang for your buck. They may not have as high a clock all the time, but they are way more efficient, ie, more IPS (Instructions Per Second).

The jumpers can come in handy. As I said the cable is for ICSP, in circuit serial programming. It lets you program the chip while it is still in the circuit. I wouldn't worry about it, just plug the chip right into the programmer

Basically, look at the datasheet and see where the power inputs are. Then just hook it up to a source, like a battery, that is within the power limits. (I usually run mine off 2-4 AAs).

It could come in handy i guess... if you mean do you need it to generate a clock, you can use the internal clock on the PIC, or hook a crystal to it.

You will want need some random caps and resistors, wires, and such... that's basically all you need.

LCD screens usually run on a controller, using a few lines for serial communications. You can get them with up to 40 or more pins. Check the datasheet on your chip to see what it actually has for I/O.

No big deal, until you go to solder it to a perf board.

Well, you push the wires/chips in, it's somewhat strong... good enough for testing with it sitting on a table or such, but not good for field use. You will want a perf board or PCB board, and use that. I made a GBA multiboot uploader, powered by a PIC.... it's in an enclosure on a perfboard, with traces I made out of solder. I can upload some pictures if you're interested.

Big fat ugly traces

Luckily, not many were needed. Please excuse the crappy webcam shots, my digital camera isn't working right.

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As long as it's within the min/max VDD it should work fine. VSS is the negative ground pin... just hook them to the - side of the battery.

As far as the crystal stuff, it will provide a more stable clock and allow you to run the PIC at higher speeds than the internal clock. You have to guess what caps/resistors you need to get the intenral clock to go at the speed you want.

Thanks again BAF, I really appreciate your help.

Another question: I'm trying to figure out what IR emitter/sensor to get. For laser tag I obviously want these things to have good range. They'll be used in combination with a lens to focus the beam. MilesTag uses the TSAL-6100 and TSOP-4840.
But are those any different from: these from SparkFun? And if so, how? They're both 940nm, but I'm assuming they're different somehow. ... besides the angle. The angle I can deal with with the lens, I suppose.

More question (sorry): Is this LCD okay? In other words, can I just wire it up to the controller on 11 of the I/O pins, type some code, and away I go?

Finally: So do I wire both VSS pins to the negative side of the battery?

I really appreciate all the help.