Time Chain — the singleplayer Co-Op game
A game jam entry about time travel
Game Jam theme:
Chain Reaction, organised by Brains Eden UK
Responsibilities:
- Project Lead
- Gameplay programming
- Game Juiciness
Development Time: 48h
Our take
Imagine if every time you die, you time travel to the beginning of your life, only to find out that now you exist in parallel to all the previous yous. Now say that you have a short life span and can only do one action in that life span other than move around. That is roughly our game loop, you play as a one-wheeled engine that has one throwable bomb and can self-destruct on command. It is a puzzle-platformer where you use your past actions to influence your current ones. So how do you do that, well you bounce from the grenade impact, meaning that if you are close to an exploding grenade or self-destruct from a previous ghost you are propelled directionally by the blast. Like rocket jumping but with grenades.
This is the first game jam where the game design idea is mine. It came to me when we realised that a chain reaction is can only happen if there are two or more entities manipulating events, and as we wanted to stick to single player, hence the Co-Op joke :)
The tech behind the jam
Ghost Replay system
Immediately after settling on the concept, my first order of business was to research the Replay system in UE4 and see if it would be easy enough to set up for the project, Unfortunately by default replays can only be record in standalone mode and required some C++ project setup, which means time lost in configuring the environment for my team + less iteration time as you have to wait for standalone editor test to load every time, it wasn't worth the risk. So I went along with the backup implementation — record the actions of the player ourselves. Which means splines and asynchronous events. Player movement is recorded every 0.2 seconds as points on a spline, along with timestamps for each point, which then is used to determine the speed at which the player moved between those points so that the overall timing matches up when replaying the playthrough as a ghost character. And as for the bombs and self-destructs, their event timestamp is recorded, along with the necessary data, which in the case of the grenade is the camera forward vector used to launch it. These events are asynchronously played back using the correct timestamp. As because both systems have measures in place to make sure that timings are correct during the replay, that is basically the system.
Polish and juice
With the spline recording system, something really cool essentially became free — the rewind effect, when you self-destruct, instead of just respawning you, your current actions are rewinded to the start and then you spawn anew. The other highlight is the player camera, everyone at the event was amazed by the camera feel and overall polish of the game, and as what I did was essentially super easy, I decided to do a breakdown/tutorial on my twitter.
The game features a short tutorial and a single level and is completed in between 10–15 minutes, so feel free to download it and give it a go :)
