FlashBoss

Build vocabulary with spaced repetition and boss fights

FlashBoss is a serious study tool in RPG armor. Learn the most useful words of a language one example sentence at a time, with audio on every card. Words come back just as they begin to fade, and every cluster ends in a boss fight you can only win by facing your hardest cards. Win, and those words graduate: your deck gets smaller as you go.

To learn a language you need surprisingly few things: trust that your effort won't be wasted, exposure to new language right at the edge of your comfort zone, re-exposure as it begins to fade, and a reason to come back to your desk, where the learning happens.

Speaking is a real-time strategy game; FlashBoss is the same game turn-based. You make the same moves — recall, build, answer — but with time to think.

FlashBoss in its own window

On Windows, Mac and Linux, FlashBoss now opens in its own window. It is still optimized for the numeric keypad, and now you can click menu options and answers too. Resize the window or go fullscreen (F11). An on-screen tutorial cast shows which key does what (F8 hides it), and a hotkeys panel, the pronounce window, the Esperanto analyzer and the language menu all open inside the window. Arabic, written right to left, plays here.

The classic terminal version is still there as the second launch option. Both run the same engine on the same heroes, saves and progress, so you can switch at any time. If anything misbehaves in the new window, launch FlashBoss Terminal and carry on, and please tell us what happened in the discussions.

What you get

Courses from first words to functional reading and listening: 3,000 words in German, Spanish, French, Italian, Esperanto, English and Swahili, and a 2,000-word reading course in classical Latin. Audio on every card, and the cards, notes and lessons in English, German, Spanish, Japanese, Simplified Chinese, Russian or Arabic (Arabic in the new window).

Five courses ship inside the base game: German Core (the first 1,000 words of German, with a cultural integration section), Esperanto Core, Toki Pona, English Advance and English Adept.

Choose your master

The Masters

Cards a day

New words

1,000-word pack

🐺 Luna*

8

3

~1 year

🐉 Shen*

13

5

~8 months

⚫ Claude

13

5

~8 months

🦉 Odiin

21

8

~5 months

🦊 Kitsune

34

13

~3 months

🦅 Aquila*

34

13

~3 months

Your master sets how much you study each day; the cluster bosses decide when you move on. FlashBoss is designed to move at your own pace, so these values are approximate. Change your master anytime to speed up, or to take it easy for a while.

Bossy masters will force your hand occasionally (guided study).

How it works

Each card sets a target word in example sentences at your current level. Words come in thematic clusters, and every cluster ends in a boss fight: one step forward for a correct answer, two steps back for a mistake, with your easiest cards dealt first and your hardest last. You can't defeat a cluster without facing your hardest cards. Memorize the target word, not the sentence — the grammar comes back on its own. Finish early and the Grimoire lets you bring tomorrow's cards forward; do that and you bank a day of Drive, which keeps your streak alive on a day you can't make it to your desk.

After completing your first cluster, revision mode becomes available. At the end of your first tier: the Bossrun! Fight all tier bosses in sequence to keep sharp and challenge your personal best. Personal records are kept locally while the Steam achievements platform is built out.

Pronounce anything

FlashBoss ships its own neural text-to-speech engine, and it is not locked to the cards. Press Ctrl+P on any screen to open the pronounce window: paste in any text — a letter, a homework sentence, a word that scares you — and hear it spoken properly, or save the audio to keep. Use it as a read-aloud tool for anything you are studying.

Global keys: Ctrl+L — interface language · Ctrl+P — pronounce window · Ctrl+E — Esperanto word analyzer · S — audio on/off during review.

Free resources online

Free word lists and full lesson lists for every pack are online, with a sample of every voice and a playable boss-fight demo. Link in the right sidebar; the manual link opens the voice samples.

The packs

Included in the base game:

German Core — the first 1,000 words of German, including a cultural integration section.

Esperanto Core — one of the easiest languages to learn; 1,000 words goes far.

Toki Pona — the complete course in the world's smallest language. Learn it in a week; think in it for life.

English Advance — don't get held back. Paperwork English: the forms, letters, appointments, and offices that run a life. 500 words. Choose American or British English in the language preferences and it teaches that country's own paperwork vocabulary (ZIP code or postcode, wait in line or queue here): an excellent way to prepare for life abroad.

English Adept — become adept in English. For anyone with the quiet ambition to articulate themselves well: 1,000 words chosen for their cultural weight and their precision.

Further FlashBoss content:

Full courses in German, Spanish, French, Italian, Esperanto and Swahili — Core, Pareto 1 and Pareto 2, 3,000 words, beginner to advanced.

Latin Core and Latin Pareto — a 2,000-word reading course in classical Latin, with its own trained voice.

English Core — English as a foreign language for German, Japanese, Spanish, Chinese, Russian and Arabic speakers: the first 1,000 words, fully playable in your language, with Pareto packs continuing to 3,000.

Latin Roots — build English vocabulary by recognizing the parts that make the whole. 1,000 words over 500 cards.

German Roots — the Germanic backbone of everyday English. 1,000 words.

Norman Roots — the French that arrived in 1066 and stayed. 1,000 words.

Greek Roots — the vocabulary of science, medicine and philosophy. 1,000 words.

The Guide — not a language at all: the rules a game master needs in their head, as flashcards. 1,205 cards, 5E compatible. Not yet available in Arabic.

The Guide Part II — spells from cantrips to level 9, creatures and magic items: 925 more cards.

Coming next — 3,000-word courses in Russian, Indonesian, Greek and Ancient Greek.

English text is American by default. The Voices: English (F) pack speaks British English and switches every English text field to British spelling by itself; prefer British text without the voice, and it's one setting away: Help & Options → Preferences → Language preferences → English spelling.

The Voice: Castilian Spanish (M) pack gives every Spanish card the sound of Spain. It takes over as soon as it is installed; switch voices any time in Preferences.

Nominated for the TOMMI 2026

FlashBoss is nominated for the TOMMI 2026, Germany's children's and youth software award, in the youth education category. An expert jury of educators, researchers and journalists chooses the nominees. Children and teenagers choose the winners, testing every nominee in around 40 public libraries in Germany and Austria.

In the jury's words: "Whether it's English, Spanish, or Latin, exercises and language challenges become part of the user's own adventure, creating a motivating framework for learning."

Developer Note

FlashBoss is a sanctuary for learning as much as it is a game. Most of the pleasure to be taken comes from learning the satisfaction of pattern recognition at your own pace. FlashBoss is also a 'question' generator. When something specific puzzles you — why this case, why that word order, why the ending changed — this question will allow almost any AI to give you the exact answer you need, at a level you can understand.

— Master Odiin (last updated October 10, 2026)