The challenge mode can be played with up to 4 players locally
In Tachyon Project you take control of Ada, a software program that has taken conscience and that was designed to hack into the most secure servers on Earth. After some rather mysterious events, Ada is thrown out of the test server where it was living and out into the Internet, but when she tries to go back there she finds she's unable to. She'll then start a journey to uncover the truth behind what happened to her creators, which she considers her parents. In the process she'll find out that things were a bit more complex than she initially thought.
The game's story mode features progression, including unlocking new weapons, secondary weapons, and perks as you progress, and uncovering the story behind Ada's creation. There's also challenges that present you with unending hordes of enemies to try for the best score and compete in leaderboards.