Tarc looks like a game on the surface — XP, streaks, gems, a leaderboard — but every one of those mechanics exists to support one underlying system: a daily lesson loop paired with spaced-repetition review. Here's how the pieces actually fit together.
Each time you open a course, Tarc serves a short lesson built from two ingredients: new material (the next unlearned word, letter, or grammar point in the course sequence) and review (material you've already met, due for another look). You never get a lesson that's 100% new — review is baked into the structure from day one, not bolted on as an afterthought.
XP is a running total of correctly completed lesson content — a rough proxy for how much you've actually practiced, not a currency with its own logic. Gems are earned alongside XP and spend only inside the optional cosmetic shop; neither one gates course content, so nothing about progressing through a course depends on how many you've accumulated.
A streak counts consecutive days with at least one completed lesson. The daily goal ring on the Learn tab shows progress toward a small XP target for the day — small deliberately, since the target is designed to be clearable in a few minutes, not to demand a long session every day.
Underneath the visible lesson content, a scheduling system tracks each vocabulary item and rule you've met and estimates when you're likely to start forgetting it. Instead of reviewing everything on a fixed weekly cycle, items you've gotten right repeatedly get spaced further apart, while items you've missed come back sooner — the review queue for tomorrow's lesson is built from that estimate, not a fixed syllabus.
Outside the main lesson path, dedicated practice modes (vocabulary drills, listening exercises, matching games) let you reinforce material on your own schedule, and daily quests give small, optional extra goals — both are supplementary to the core loop, not required to progress.
See also the reference page: Learn Languages with Tarc.
Inside them — each daily lesson is built from a mix of new material and review items chosen by the spaced-repetition schedule, rather than review being a separate mode you have to remember to open.
No — they're progress indicators and shop currency respectively, not gates. Course progression depends on completing lessons, not accumulating a certain amount of XP or gems.
Your course progress and spaced-repetition schedule aren't reset — only the consecutive-day streak counter is affected. You can simply resume lessons the next day.
No — they're optional supplements. The core lesson path is what actually moves you through a course's levels.