Element Card Battle

How to play

1. The name of a substance (for example “Water” or “Carbon dioxide”) appears large on the sign at the top. Its chemical formula (H₂O, for example) is shown faintly on the board below it.
2. Five to eight element cards are dealt at the bottom. Each card is a block: an element symbol with a small number (H₂, O, O₃ and so on).
3. Play the matching cards in order, starting from the left of the faint formula. For water, play H₂ → O; for sodium bicarbonate, Na → H → C → O₃.
4. A correct card flies to its place in the formula, and that part lights up. A mark shows where the next card goes.
5. Play the last card and the answer is correct right away. The spell for that substance hits your rival.
6. A wrong card (H with the wrong number, a look-alike such as Na, or a card out of order) bounces back to your hand and costs 1.5 seconds.
7. If time runs out, your rival hits you and you lose a life. You have three lives; when they run out, the run ends. The run also ends when you reach 1,000 questions.

Questions and difficulty

Each question asks for one substance from middle school science. You start with substances of one or two blocks such as H₂ and H₂O and a hand of five cards. As you go, substances with more blocks such as H₂SO₄ and NaHCO₃ appear, and your hand grows to six, seven and eight cards.

Decoy cards are chosen first from the same symbol with a different number (H or H₃ for H₂, O₂ or O₄ for O₃), then from look-alike symbols (N and Na; C and Ca, Cl or Cu), and then from other elements.

The time limit is “2.0 seconds to read + the number of blocks × time per card”. The time per card starts at 2.0 seconds and shrinks to 0.8 seconds.

Score and ranking

• Score: base points (number of atoms × 10) × a speed bonus (1× to 2× depending on the time left, after subtracting the time lost to wrong cards), × a streak multiplier (from 1×, up 0.1 per correct answer in a row, up to 3×). Running out of time resets the streak.
• Results: your score, substances made, best streak, average answer time, ranking position, and the list of substances you made.
• Ranking: everyone’s personal best, top 50. Substances made and average time are shown next to the score. Your own row is highlighted.

At streaks of 3, 6 and 10 the effects level up and the spells get flashier.

Substances

The game features 18 substances: hydrogen, oxygen, nitrogen, chlorine, water, carbon dioxide, sodium chloride, hydrogen chloride, copper(II) oxide, magnesium oxide, iron(II) sulfide, ammonia, sodium hydroxide, sulfuric acid, sodium bicarbonate, sodium carbonate, silver oxide and copper(II) chloride. Each substance has its own kind of spell. Water gives a stream of water and hydrogen gives fire. Hydrogen chloride, sulfuric acid and sodium hydroxide give a dissolving acid rain. Salt, copper(II) oxide, iron(II) sulfide, sodium carbonate, silver oxide and copper(II) chloride give crystal lances; oxygen, nitrogen, carbon dioxide and sodium bicarbonate give wind; ammonia and chlorine give a poison mist; magnesium oxide gives light. Substances with more atoms make bigger spells.

Your rivals are Kai the Hothead, Shion the Honor Student, Momo the Prankster and Rei, Council President. Defeat one and the next steps in, until your run ends.