Time is an equation, and you're here to solve it. 1920s Chicago detective Zachary Burton must defeat the Combine's attempts to influence humanity's past in the 20s, 40s, and 80s, and then achieve victory in the present - all the while pursued by a dark mirror of himself.
"Sometimes the places we know most are the places we like least."
You are Zachary Burton, a 1920s police detective down on his luck and running on fumes. The Metro-Gang has had their grip on the seedy underbelly of Chicago unchallenged for so long. More and more people are going missing. People are scared, and the system isn't working. A loaded .38 Magnum and a suave fedora are your only allies in the dark, rainy night.
What was meant to be a little street justice unfolded into a conspiracy that transcends space and time - the Combine, tired of losing ground in the present, have started to meddle with the past. Not just 1920s Chicago is under threat, and before Zachary can call the case closed, he'll be whisked through the 40s and 80s. Then, he'll be sent to the source - City 17, in the heat of the rebellion, to set the record straight. All the while, a crime boss way past his station will keep getting in the way - determined to take you out and pursue his own ambitions.
Time is an equation - and you're here to solve it.
The Burton Equation is a Half-Life 2 mod with four chapters, set in the 20s, 40s, 80s, and during HL2. Each chapter has a unique arsenal of weapons, with a pistol, SMG, and "special weapon" for each period. Various Combine enemies will be stationed in each period to bar your way, in tight, close-quarters combat intended to channel the "retro shooter" vibe.
Power-ups can be obtained throughout your journey, giving you an overheal or double damage to take challenging engagements. Meanwhile, your kick can clear obstructions, be they living or otherwise. A unique boss enemy, with tactics and capabilities echoing that of the player, will bookend your journey.
Every level begins with a set of comics created for the mod by Creative Arts Professor, Adam Rogers, which vary in style depending on the period, and are accompanied by Zachary's scene-setting monologue. Each era has period appropriate music, which in the case of the 20s boss music, 80s tracks, and HL2-era music, was all composed newly for the mod. Lastly, research was undertaken as to the kinds of materials, vehicles, and constructions that would be used in each period to avoid anachronisms and maximise immersion (within the confines of an action-shooter!)