Refill Hearts
Free players do not regain hearts over time. Refill all five hearts with a one-time purchase.
Your engineering path
Pick a sector, clear units, earn XP — Unit 1 is free everywhere.
Today's missions
Daily goal
0 / 50 XP
Category
Unit 1 is your free demo. PRO unlocks every unit.
Loading…
Out of Hearts
Hearts do not recover on their own. Buy a refill, or get Individual PRO for unlimited practice.
Leaderboard
Compete in your weekly league. Top ranks promote; bottom ranks demote.
Achievements
0 / 11Unlock badges by practising and hitting milestones.
Your stats
Lifetime
Progress by sector
Settings
App language
Menus and buttons only. Lessons stay in English — that is the point.
Microphone questions
Pronounce terms aloud in quizzes. Turn off to skip them entirely.
Sound effects
Ding on correct answers, buzz on misses, fanfare on lesson end.
Username
Your public @handle on the leaderboard. Letters, numbers, dots, and underscores.
Daily goal
XP target per day. Completing a lesson keeps your streak; the goal is a bonus target.
Subscription
Paid for PRO but it is not active yet? Restore your purchase.
Subscription
Loading…
Billing managed by Lemon Squeezy.
Symbol Library
Search technical symbols by name, category, or schematic ID.
Boss Portal
Invite teammates by email and track their progress.
0 / 0 seats used
Invited emails
Shop
Power-ups and Voltlingo PRO.
Streak Freeze
Miss one day without losing your streak. You can hold up to two freezes. New engineers start with one free freeze.
400 XP
Individual PRO
Personal subscription for solo engineers who want the full curriculum, unlimited hearts, and every unit unlocked.
- Unlimited hearts — never get locked out
- Unlock every unit across every sector (pass each unit to open the next)
- Full curriculum for solo engineers
$4.99 / month
Group PRO
For team leads, trainers, and bosses. Purchase seats, invite members by Google email, and manage your team in the Boss Portal.
- All Individual PRO perks for every invited member
- Boss Portal to invite by Google email
- Track team XP, streaks, and unit progress
- One admin seat included
Need more than 200 seats? Contact us