Helix Jump is safe for children, but some ads may not be suitable for children under 12. Parents are often worried about ads, in-app purchases, and in-game content. Helix Jump is ranked 12+ on iTunes for the following items from the ads you see.
Uncommon / mild medical information / treatment
Recommendations or rare/moderate use of alcohol, tobacco, or drugs
Unusual/slight nudity and sexual content
Strange/mild themes of fear
Sometimes / moderately lazy games
Rare / mature / suggestive themes
Unusual/mild comic or fantasy violence
Rare / moderately realistic violence
When I played, I only saw ads for other age-related games. If you do not pay for the ads, the game content is suitable for ages 4+.