This post is a reference for me so I know what features to work on next, as well as catalogue what is left. I'll edit or repost this for newer versions or whatnot.
Engine Build 55: Level Renderer:
-Obstactle Collision Mask
-Noncollision Display Blitters
-Gravity Zone Exporter
-Parallax Background Layers
-Backdrop Loader
-Object Loader
-SFX Preloader
360 Degree Movement:
-Gravity Zones
-Gravity Angle Deducer
-360 Air Movement
-360 Ground Movement
-Jumping
-Grappling Hook
Platforms:
-Grapple Blocks
-One Line Platform
-Orbital Platform
-Spinning Platform
-Spin Platform Corrector
Environmental:
-Lighting Blitter Overlay
-Water Blitter Overlay
-Water Floatation
-Space Dust
Player Attacks:
-Chain Weapon/Temporary
Enemies:
-Enemy 360 Movement AI
-Enemy Jump Movement
-Player Death Effect
-Enemy: Hopper
-Enemy: Purple Goo
Time Rewind Engine:
-Position/State Tracer
-Position/State Rewind
-Event String Rewind Parser
-Sound Effect Rewind
Frame Display:
-Efficient Rotate Pixel Shader
-Smooth Rotation Camera
-Multiple Camera Movements & Controls
-Underwater Shader/Rewind
Pause Menu:
-Pause Effect
-Rewind Speed Switcher
New Feature: Camera System
-Allows 4 different camera types (point to point line either free rotation or fixed angle, and singular point focus either fixed or free), as well as bounding boxes for sides of maps/walls and such. It also includes the ever popular "roaming camera", which peaks slightly ahead in whatever direction you are moving, and automatically updates to smooth this for 360 degree travel and fast areas.