I managed to find some great Post process/Shaders for both UE4 & Unity with the help of Scribble . They are a kind of overlay which will add a pixelated look to the game which could match nicely with the Lo-fi aesthetic of the Jam. Here's the links - 

UE4's Pixelated Post Process - https://github.com/DaveFace/UnrealRetroShaders

Unity's Pixelated Shader - https://assetstore.unity.com/packages/vfx/shaders/fullscreen-camera-effects/pixe... or a modified version of it - https://github.com/bengreenier/Unity-Pixelation-v2