Hi SzechuanSteve!
Those are all excellent ideas and I will be revisiting this post when designing the larger game. I can't wait to make and implement the head-to-head gameplay!
Those are some awesome ideas for powerups. I did think of invulnerability but ended up scrapping it, ironically for what I perceived to be balance issues. I love the jumps heavier/lighter idea, and flying is excellent too! I am very grateful for your suggestions. Thank you so much for playing!
Best,
Brandon from TheIndieDream