Acecourt: the browser tennis game where the serve is a skill, not a button

01  What it is

Acecourt is a real-time tennis game that runs in a browser tab. You play one short singles match against the computer — arrow keys or WASD to move on a keyboard, a drag circle and two buttons on a phone — and the ball is simulated rather than animated: gravity pulls it down, air drag slows it, and spin bends its flight and changes how it kicks off the bounce.

It is deliberately one match and no more. There is no career mode, no tournament bracket, no locker room. You pick an opponent, play a set, and get a card with the numbers on it. That shape is the point: it fits into the gap between two other things you were doing.

Nothing is installed, there is no account, and the whole match is simulated on your own device.

02  The serve is a timing game, and it decides points

Serving is not a button you press to start a rally. You press once to toss the ball, and a meter starts sweeping out and back across the screen, roughly every seven-tenths of a second. You press again to strike, and where the marker was when you pressed is your serve quality.

The middle band of the meter is the good zone, and the very centre of it is the ace window. Strike there and you get maximum power and the tightest placement — a perfectly struck serve can go past an opponent untouched. Miss the middle and quality falls away toward the edges: less pace, more scatter, and a real chance of pushing the ball long. A missed serve is a fault, and two faults is a double fault and a free point for the receiver, exactly as in the real sport.

If you never strike at all, the game will not leave you hanging: after about two-thirds of a second the toss resolves into a safe, gentle serve. It keeps the point moving, but a serve that soft is one a decent opponent will attack. Holding a direction as you strike aims the ball toward the outer corner of the box instead.

03  Two shots, and no aiming cursor

You have a drive and a lob. The drive is flat and fast with topspin on it, so it dives late and kicks forward when it lands — the shot you use to hurt someone. The lob floats higher and slower with backspin, hangs in the air, and lands deep, which makes it the shot you use when you are stretched wide and need time to get back into the middle.

There is no crosshair anywhere in the game. Where the ball goes is set by where you are moving when you swing: left and right on the stick places the ball left and right, and the shot type sets the depth — a drive lands around seven-tenths of the way to the far baseline, a lob closer to nine-tenths, with a small nudge deeper or shorter depending on whether you are pressing forward or back. You aim with your feet. It takes a few points to trust that, and then it feels like tennis rather than a menu.

The swing itself has a clean-hit window. If the ball is within about half a metre of you when you swing, the strike quality jumps to near maximum: a hard crack off the strings, the camera kicks, and the ball streaks. Swing late or early and quality falls off with the distance, so the ball sits up slower and softer and your opponent gets to it. Timing beats mashing, consistently.

04  The opponent is a decision loop, not a difficulty slider

The AI does three things each moment, and all three use the same physics you see. It predicts where your shot will land, runs to the intercept point, then chooses a shot type and a target — usually somewhere you are not. It is not reading your inputs and it does not teleport: the game's own tests assert that its prediction only ever sees the ball state it would legitimately see, and that it never moves faster than its tier allows.

Four opponents, and the differences between them are honest dials rather than a hidden cheat. Easy starts reacting about a fifth of a second late and only reads about half the flight, misplaces by roughly a metre, and hands you an unforced error on one routine ball in seven. Hard reacts in about a fortieth of a second, reads the whole flight, misplaces by about twenty centimetres, and gives you almost nothing — roughly one free error in forty-five. Pro tightens the same dials further: the tightest lines, the fewest gifts, and a serve that is a genuine ace threat.

One detail is worth knowing before you pick a tier. Your own movement is capped at 7.6 metres a second. Easy and Medium move slower than that, so you can out-run them. Hard and Pro move at 8.8 — they cover the court faster than you do. On the top two tiers you do not win by running; you win by making the opponent run and then putting the ball where it just left. Pro is deliberately kept at Hard's footspeed, because the designers found that a faster opponent simply overran the ball and mistimed its own swings — so Pro's difficulty is precision and relentlessness instead, which makes it a hard step up rather than a different game.

The tier strengths are measured rather than asserted. The project runs seeded opponent-versus-opponent matches in its test suite: Hard beats Easy in at least six of seven seeds, and Pro beats Hard in at least seven of ten. Pro is stronger, but by a narrower margin than the gap below it — which is what you would hope for from a top tier.

05  The card at the end, and where your record lives

When the match ends you get a numbers-only card: the score, the difficulty, your longest rally, how many aces you hit, your fastest serve in km/h, your current win streak and your best one. There is no room on it for typed text, and that is by construction — every string on the card is either a fixed label or a number the game computed. It is generated at 1200 by 630 pixels, so it drops into a chat or a post without being cropped, and it can go straight out through your phone's share sheet, be copied as a link, or be downloaded.

The link it shares carries the difficulty with it, so a friend who taps it opens the game already set to the opponent you just beat. There is also a seed parameter if you want to pin a specific match and replay the same one; otherwise every new match is a fresh draw.

Your record — streak, best streak, longest rally ever, fastest serve, and wins and losses against each of the four opponents — lives in your browser and nowhere else. Win and the streak grows; lose and it resets to zero while your best streak stays on the board.

06  Five things that actually win matches

Tennis games reward a few habits far more than any single spectacular shot.

• Spend your first match on the serve meter alone. It is the only part of the game with a window that narrow, and a serve you time well is the cheapest point you will ever win.
• Arrive early rather than swinging early. Most lost points are late feet, not bad timing — the clean-hit window is about half a metre, and you cannot use it while sprinting to catch up.
• Serve or drive wide, then hit behind. The opponent commits to an intercept point, so the ball that lands where it just was is worth more than the ball that lands where it is going.
• Read the shadow, not the ball, to judge depth — the ball is tiny near the top of its arc, and its shadow on the court tells you the truth about where it will land.
• On Hard and Pro, stop trying to hit winners past a player who barely misses. Move them corner to corner, use the lob to buy time when you are stretched, and wait for the ball you can actually put away.

07  Questions people ask

Is Acecourt free, and do I need an account?

Free, and no account. It is supported by ads shown away from the court, there is nothing to install, and there is no sign-up or login at any point.

Does it work on a phone?

Yes. On a phone you get a drag circle for movement and buttons for Swing, Lob and Serve, in both portrait and landscape. On a desktop the controls are the arrow keys or WASD, Space or J to drive, Shift or K to lob, and Space to serve.

How is the scoring different from a real tennis match?

Points are real tennis — 15, 30, 40, game — but the set is short so a match fits in one sitting. It is No-Ad: at 40-40 the next point takes the game, with no advantage and no deuce loop. The set is first to four games, and you have to win by two; if it reaches 3-3 you play a seven-point tiebreak, which is won by two clear points and capped at ten.

How long does one match take?

Structurally, a set is at least four games and at most seven plus a tiebreak, so it is a bounded, single-sitting game by design — there is no way for a match to run away from you. Individual points are capped too: if a rally passes about twenty seconds of play, the point is awarded rather than allowed to continue forever.

Are the four difficulties genuinely different, or is it just a label?

Genuinely different, and measured. Reaction time, how much of the ball's flight the opponent can read, placement error, unforced-error rate and serve-fault rate all change between Easy, Medium, Hard and Pro. The project verifies it with seeded AI-versus-AI matches: Hard beats Easy in at least six of seven seeds, and Pro beats Hard in at least seven of ten. Pro keeps Hard's footspeed on purpose, so its advantage is precision and consistency rather than raw speed.

Is anything sent to a server, or is my record public?

Nothing is sent anywhere. The match runs entirely in your browser, and your stats — wins, losses, streaks, longest rally, fastest serve — are saved in that browser's local storage only. The result card can be shared, but it is generated from numbers on your device and contains no text you typed, because the game never asks you to type anything.

08  More from the shelf

• Fiveaside — Score past the keeper. Post the scoreline.
• Tilewright — Draw seven tiles. Outword the AI.
• Chess — Beat the engine. Post the win.
• Tierforge — Drag anything into tiers. Post the card.

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