Fill the Fishtank
Draw one line to route water from the tap into the fishbowl without wasting drops.
Each level shows a tap, pipes and a target vessel; drag to draw a single channel line; water flows along it; if it reaches the target cleanly with minimal ink, you bank stars.
Drag to draw one line (one thumb).
Underwater fishtank rescue with bubble obstacles and goldfish targets (skins over Happy Glass's draw-physics core).
Happy Glass holds 4.4 stars on Poki with 591K ratings, proving draw-a-line-to-fill is an evergreen mechanic.
Happy Glass proved the draw-line-to-fill mechanic at scale (591K Poki ratings), but Fill the Fishtank is essentially a reskin with a fishbowl target — no new emotional twist beyond renaming the sad vessel.Happy Glass Poki page confirms the mechanic and its broad rating base ↗Original Play Store listing for the same draw-to-fill mechanic ↗
Visual water-flow is inherently watchable and one-thumb friendly, but searches did not surface strong current short-form/streaming evidence for the mechanic; Poki's 591K ratings show steady web reach, not peak viral spikes.Poki ratings indicate sustained web/browser virality over years ↗
Single-line drag physics is a well-trodden 2D implementation; entire genre demos exist and the original ships as a lightweight mobile title.Browser port demonstrates how trivially the mechanic clones to web ↗
Lion Studios (Happy Glass publisher) ran the standard hypercasual rewarded-video + interstitial stack; eCPMs remain viable for puzzle subgenre, but a saturated niche compresses fill rates.Sensor Tower profile confirms commercial tracking on the original draw-to-fill app ↗
Market is clearly crowded: '19 apps like Happy Glass', '30 alternatives', and a public 'Draw to Fill' web clone all coexist — mechanical whitespace near zero, only thin thematic whitespace (fishtank skin).19 listed Happy Glass alternatives, indicating heavy cloning ↗Softonic lists 30+ similar Android games, showing market saturation ↗Web/game-trend 'Draw to Fill' cloner still actively competing in the category ↗