EARLY ADOPTER BONUS

German Core FREE for a limited time. Esperanto Core, English Advance and English Adept included free permanently.

About This Game

FlashBoss: Spaced Repetition and Boss Fights

Listen · Read · Repeat · Rate · Fight: FlashBoss is built for passive language skill acquisition — reading, listening, and understanding language in use. 3,000 of a language's most useful words, presented with naturally structured, level-appropriate example sentences. Reference lessons unlock what you're reading, and Piper text-to-speech audio on every card.

How it works

FlashBoss is built on comprehension from context. Every card pairs a target word with example sentences at a level you can follow — grammar, collocation, and usage shown together in one line. Rate each flashcard from 0 to 5. Spacing follows Fibonacci intervals — the better you know a word, the longer before it comes back. Words are grouped into thematic clusters, and each cluster is gated by a boss fight: a see-sawing battle where correct answers drive you forward and mistakes push you back. Win, and the cluster graduates. Your deck gets smaller over time.

The word lists themselves are frequency-selected, and weighted for usefulness: the most efficient words, arranged as they are needed to expand your comprehension. You will read many thousands of words worth of example sentences, and learn context without stepping too far outside of your comfort zone.

Maintain your daily streak to earn Drive — banked days off for when life interrupts. Five to thirty minutes a day depending on your choice of master.

The mechanics 

Each card is a cascade. First, you see the target word (with article colour-coded to gender in gendered languages). Then an example sentence in the target language, the same sentence translated into English, and the translation of the word itself. Rate the word 0 to 5 — this sets when you see it next. Press 7 for the reference menu, 8 to see optional usage notes, 9 to bail. FlashBoss is designed to be waiting right where you left it if you quit mid-session, resetting at midnight.

Words are grouped into thematic clusters. When a cluster reaches 80% mastery — defined as a 13 day interval per card or greater — a boss fight unlocks.

Boss fights

The boss stands on a platform and you're there to shove it off. Sumo rules. Multiple choice, 1–8. Correct answer: you advance one position, pushing the boss back. Wrong answer: you slide back two. Get pushed off the left edge and you're locked out of that cluster's fight until tomorrow. Push the boss past the right edge and the cluster is conquered.

Positions are difficulty-rated. You start on the left with your two easiest cards from the cluster — the ones you know best. Reach the middle and the hardest cards arrive: your weakest words, right when the stakes are highest. Get the hardest card wrong and it gets reclassified as your easiest card. Unfortunately, that means it's waiting for you. You cannot win a cluster fight until you have mastered your weakest cards.

Your deck gets smaller

Defeat a cluster's boss and its cards are purged from your main rotation. Permanently. They migrate to a voluntary revision mode where the Fibonacci ladder keeps climbing for anyone who wants them — but they never again add to your daily streak requirement. Your deck gets smaller as you progress through it. 

Not just a word list

Every FlashBoss language pack is built the same way. Two or more independent frequency sources cross-referenced — one academic, one corpus-derived from natural contemporary speech. A multi-pass selection procedure that catches and excludes phantom vocabulary: inflected verb forms showing up as nouns in raw frequency data, accent-stripped orthographic ghosts, homographs where the wrong sense would dominate. Zero duplication across the entire 3,000-word pack family. And cultural curation by hand.

Words are sequenced. Grammar is explained progressively — example sentences only use structures the learner has already encountered. Reference lessons fire at the point in the card sequence where they unlock what you're about to read. The result: you guess what a word means from context, and find out right away whether you were right.

Choose your master

Six masters, six daily paces — from Luna's gentle pacing to Odiin's stoic wisdom. Pacing ranges from 8 to 34 cards a day, roughly 5 to 30 minutes.

• 🐺 Luna — gentle and encouraging, 8 cards per day

• ⚫ Claude — analytical and precise, 13 cards per day

• 🐉 Shen — stern and direct, 13 cards per day

• 🦉Odiin — master and founder, 21 cards per day

• 🦊 Kitsune — playful trickster, 34 cards per day

• 🦅 Aquila — noble and disciplined, 34 cards per day

Some masters are bossy: they cap boss fights at three per day to protect you from burnout. Others are advisory: they'll warn you it's a bad idea, then let you do what you want. One bossy and one advisory at each difficulty tier, so your temperament and your pace can be chosen independently.

Drive and the grimoire

Life interrupts. FlashBoss has two mechanics for this.

The Grimoire is a pre-pay spell. Sit down today and do tomorrow's full projected load — dues plus new cards — in a single session, and you bank a day off. Don't finish what you started, and you're locked out of the Grimoire until tomorrow. No half-credit.

Drive is the currency the Grimoire earns: banked streak protection for days when life wins. You choose when to spend it.

What's included

Three 1,000-word packs and one 500 word pack ship free with the base game. Every card includes a definition or translation, example sentences, and optional usage notes. All presented with high quality Piper text-to-speech audio. 

German Core

The first installment of the German language pack: 1,000 words across five tiers, A1 through A2. Enough to walk into an A2 immersion class on day one and follow most of what's happening. Gender colour-coded articles throughout. Thorsten-medium Piper TTS — MIT-licensed, clean and consistent. 

Esperanto Core

1,000 words will get you very far in a language built to be learnable. Regular morphology, no gendered nouns, no irregular conjugations. Esperanto is also an ideal proving ground for the FlashBoss method itself — a language that rewards careful vocabulary work almost immediately, where progress is visible week over week. pl_PL_darkman-medium Piper TTS 

English Advance

The front door to English vocabulary building: 500 words across five tiers, aimed at the language of responsible adult life. Forms, emails, signs, official letters, and the small print nobody explains. Where Adept sharpens precision, Advance builds the floor beneath it — the practical English that paperwork, bureaucracy, and daily documents demand. libritts-high Piper TTS.

English Adept

1,000 words of carefully chosen English — chosen to sharpen the way you think, write, and speak. The difference between stubborn and obstinate, practical and pragmatic, agreement and consensus. Precise words make precise thoughts, and precise thoughts make for essays, arguments, and judgements of a higher quality. Start at the shallow end and push beyond your comfort zone.

DLC

Full 3,000-word courses per language: Core (1,000 words), Pareto 1 (1,000 words), and Pareto 2 (1,000 words). Every pack includes high-quality text-to-speech audio, real example sentences, usage notes, and structured reference lessons. 

• Spanish — Core, Pareto 1, Pareto 2

• German — Pareto 1, Pareto 2 (Core included free)

• Esperanto — Pareto 1, Pareto 2 (Core included free)

• Italian — Core, Pareto 1, Pareto 2 (rolling out April–May)

The Roots Series explains the shape of English and its European neighbours:

• German Roots — the Germanic backbone of everyday English.

• Norman Roots — the second English vocabulary, 1066 and after.

• Latin Roots — word construction from its parts, classical and scientific English. May 10

• Greek Roots — prefixes, stems, and suffixes. TBA

Useful whether you're learning a foreign language or sharpening your native one. Every Romance word in Italian or Spanish routes back to Latin; every everyday English word has a Germanic cousin in German. The Roots Series makes those connections visible.

Why terminal?

Python in a terminal. Nothing needs to load, nothing distracts, and nothing runs that doesn't need to. FlashBoss works on almost anything, with caching enabled for older machines — open the in-game help menu to learn more.

Setup

• Windows 10+ (Windows Terminal required) 

• macOS 10.15+ / Ubuntu 20.04+

• Numberpad recommended, but not required

About the development

FlashBoss is the work of one CELTA-certified teacher based in Germany, made possible by Claude.ai as a research and scaffolding partner — for word-list cross-referencing against academic sources, pedagogical structuring, card and example sentence drafting, code architecture, and voice synthesis selection. Every word list was audited against academic frequency sources. Every lesson and example sentence was reviewed for pedagogical soundness. The result is a product shaped by a single teacher's judgement, at a scale that would otherwise require a team.

AI Generated Content Disclosure

The developers describe how their game uses AI Generated Content like this:

AI was used in the coding of this game, the asset generation, brainstorming practical solutions (knowledge about opensource tts options, distribution options), and in helping problem solve most steps in the development, and application process. It allowed one developer to create a high quality, low cost educational product to greatly assist in language learning worldwide.