The main objective was to get custom laser tag gaming on an arduino based platform as cheap as possible. Kids would be able to play pickup games easily at our church. I wanted to add a lot of really useful features and the list just kept on getting longer and longer. 

The current feature set:

Everything runs on the Teensy 4.1 by PJRC

upgraded from 6xAA batteries to lipo battery with built in recharging

replaced monochrome screen to full color LCD st7789 screen

i2s class D amplifier for audio effects (using the stock speaker) 

added large vibration motor in the handle and small vibration motor embedded in the trigger

added visible laser 

added neopixel strips down each side of the gun and drilled out holes 

replaced navigation panel buttons with joystick and 2 tactile switches

added rfm69 packet radio for long range communication 

I'm still using the original housing/shell, the optics, the barrel tx/rx, the dome tx/rx, switches and triggers, but everything else inside the gun is scrapped. 

In addition, I'm using Circuit Playground Express boards by Adafruit as bases/respawn points. they also have rfm69 packet radios attached and they function as a node network to keep the current state of the game and aid in long range communication throughout the church

Game play is modeled after Halo. there are multiple weapon types: AR, pistol, shotgun, sniper, rocket launcher

each weapon has unique abilities:

the AR is full auto, low damage, low accuracy, high magazine size and high total ammo size, long reload time. Full auto has a side effect ability in that it is harder to get shot at while you are shooting, it acts like a shield. This is mainly because while a gun is sending out IR signals I have to ignore those signals being reflected back into the dome receiver. 

the pistol is semi auto, medium damage, medium range, and has the ability to lock on to a target and confirm a head shot single kill. This is accomplished using the rx barrel and a beacon sent out of every gun's dome much like how the original LTTO worked (but without the "warning warning" voice prompts). the pistol also has a silencer option.

the shotgun used to shoot out of the dome, but that didn't work as well as I expected, so now it shoots using the radio. This doesn't make it very shotgun-like: it's spread is 360 degrees, it shoots through walls, etc. But this ended up being really important to balance the guns because this means it can interrupt the AR's full auto, and it can increase damage the closer you get to your target. Too far away and it won't do any damage, right next to someone and it will kill them in one shot. The shotgun is also needs to be pumped for each shot and held for full reload with a long reload time. 

the sniper is also able to get headshot one-shot kills, with high damage otherwise. it is long range.

the rocket launcher is the highest damage and can actually kill groups of people. If you are hit with a rocket, or if a base is hit with a rocket, the blast will repeat and anything in the near area will get hit. At first I was using the dome to relay the hit, but I changed to sending a command via radio

Adding the radios was a game changer because I was able to get RSSI values that gave a good estimate as to how far away to player were to each other or how far a player was from any number of bases. This allowed me to implement some incredibly awesome features.

There are 10 bases throughout my church, and on the screen of the gun I've painstakingly drawn out a map of each level of the church. using the RSSI beacons from all the bases each gun is able to triangulate and estimate its position. Boom. Radar. 

I also use the RSSI values to set the range of certain weapons and to detect when you are at a certain base. The bases act as respawn points and the can hold bonus items, weapons, ammo, flags, etc. 

Health is regenerative like in Halo. That was one feature I really liked about the game. hopefully it will allow kids to play more and be out less. it might also teach them not to engage in point blank firefights, as they often do with the stock LTTO game. 

My version can support up to 32 players, each uniquely identifiable by the set of 8 neopixels down each side of the gun. There are 32 different teams/team colors you can join once you enter the game. At power up, you either host the game and set the rules, or you are diverted to enter your name and pick your team. you then wait in the lobby for the game to start. 

The neopixels also animate based on what weapon is being shot, and what you get shot with. If you get hit, your gun will flash that enemy's team colors. The handle rumbles for hits, and the trigger gives tactile feedback for shooting weapons. 

I currently have 8 prototypes I'm working with before I commit to building out my full arsenal. I'm adding about $70 to each gun in parts. I have all 10 bases working on the main level and lower level of the church. Still lots of testing and debug to go, but slayer game play currently works very well.

This project has been in the works for like 10 years or so, but I finally kicked it off in the summer of 2020 during COVID, and right after my first son was born. Some day I hope he gets to have just as much fun with it as I envision.