TODO

- Allow options change in the middle of playing

- Texture on ceiling and floor

- Slightly move weapon sprites up/down depending on vertical viewing angle

- Ray tracing slow when very closed to downed enemy?
  - Doesn't matter as much now with separate graphics and logic update cycles

------------

- Design some better levels: replicate E1M1 for testing purposes
  - Play with new (open source) textures

- Add more data to level pack(s): like text to be shown between missions and what background music should play
  - Add transition effects

------------

- Sound effects

- Music

------------

- Allow enemies to open doors
  - Noise crossing walls/doors to alert enemies on other side

- Put soldiers on alert based on proximity to another alert soldier, or to another enemy shooting