Update README.md

Update README.md

fixed explosion powerup

finished background color animation transitions and added explosion powerup

Almost finished color changes

added (permanent) slowdown powerup, fixed sound and bg particles bugs on pause, fixed playerpref.getint and setint performance issues.

added destroyable platforms, messaging and scoring system, and praising system

Added sound effects

Added a bazillion of things

Added Projectiles PowerUp and Background Particles. More Fixed Animations

More color changes and animation bug fixes

Added Main Menu and Pause Menu. Still bugs with player animation (respawn, turn on, and boosts)

Added First Try of debris particle systems for player and platforms. Also, added player turn on animation

Lives now reflect total lives including the current one. Slowed down the game a bit

Completed Lives system, and respawn on level border impact.