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Laser* Tag Badge

*no actual lasers used

What is it?

Laser* Tag is a community game built into the DEF CON SG1 badge. It turns the exhibit hall into a giant laser-tag arena (using infrared, not actual lasers) so every badge-holder is a player from the moment they power on.

How it works

Each badge has an IR emitter and receiver. When you point your badge at another player and fire, it sends a coded IR signal. If their badge picks it up, it counts as a hit and you score a point.

Teams

Every player is assigned to one of five team colors:

Cyan Magenta Yellow Blue Orange

Individual hits contribute to your team's aggregate score on the online scoreboard, so even casual players help their team climb the ranks.

Scoring & cooldowns

  • You earn one point per valid hit.
  • A hit is "valid" only if you haven't tagged that same opponent in the last 15 minutes. If you try again too soon, their badge blinks red three times to let you know it didn't count.
  • You can't tag members of your own team. If you try, their badge blinks three times in your team's color.

Online scoreboard

Scores are not uploaded in real time. Instead, each badge stores its own hit record locally. You periodically sync your score to the online leaderboard, where scores are aggregated at the team level and individual level.

Base station infrastructure

Physical base stations are placed around the exhibit hall areas. These base stations are internet-connected and communicate with nearby badges over ESP-NOW (an Espressif peer-to-peer wireless protocol). The base stations use periodic channel and data rate hopping. If you're curious about the internals, feel free to try and reverse-engineer the ESP-NOW packet format (it is possible).

3rd-party hardware & OpenLASIR

The IR protocol is intentionally open. The OpenLASIR project provides MicroPython and Arduino code examples so you can build your own compatible devices. The protocol is also officially supported in the Arduino-IRremote library. You can request your own dedicated device IDs to avoid collisions with official badges.

Each badge tracks hits from official DEF CON badges and from 3rd-party devices separately, so the scoreboard can be filtered by source type.

Design challenges

  • Storage & transmission limits – Badges can't store a full log of every individual hit, who delivered it, and the exact timestamp; that's why scoring is aggregated at the team level.
  • Ambient light & reflections – The MBS exhibit hall isn't a purpose-built laser-tag arena. Ambient light (especially sunlight) reduces effective shot range, and reflective surfaces can cause short-range "phantom" hits even with bad aim. Plus, we are unable to use as focused of an LED as we would like due to budget and assembly constraints.
  • No visible aiming dot – Without an actual laser, there's no dot to help you aim. The IR beam is wider than real laser tag to compensate (and also because it is difficult to achieve a narrow beam with SMD components and no additional optics).

Interop & compatibility

Laser* Tag is designed to work across badge generations. The dedicated 2025 Laser* Tag Badge ran on an RP2040; the DCSG1 Official Badge uses an ESP32-C6. The open protocol means your own creations can join the game too.

View the 2025 Archive