MatMon

Jamil Kasan
/
MatMon
on 4 Nov 2026
6
39
14
2
9506
game.m
function g = game
% CATCH RING - a one-button creature-catching game in Game Boy Color style.
%
% ROAM:   the trainer walks forward on their own. TAP to switch direction.
%         Tall grass fills the encounter meter (top right). Sparkling grass
%         starts a battle at once with better odds. Orbs on the ground are
%         +1, rocks are -1 and appear more often as your score grows.
%         You start with 3 orbs; the run ends when they're gone.
% BATTLE: a ring pulses around the wild creature. TAP when it is smallest
%         to throw a capture orb. Better timing = better odds on each of
%         the three wobbles.
% TIERS:  Common 10, Uncommon 25, Rare 50, Epic 100, Legendary 500 pts.
%         Shinies (gold) score x3. The legendary MEMBRAX is built from
%         MATLAB's own membrane(1,7): the L-shaped membrane's first mode.
%
% Structure: every game mode is its own small function. update() looks the
% current mode up in a table of function handles and calls it. Each mode
% writes the next frame (a 144x160 matrix of palette indices) into z.C,
% and render() turns it into an RGB image.
g.init = @init;
g.update = @upd;
g.render = @ren;
end

function z = init(ax)
% 39-colour palette stored as hex (RGB). Index 10/11/13 = MATLAB blue,
% orange and navy, used for the trainer and the capture orb.
Cm = reshape(sscanf(['f8f8f018182088d06048a848207038b8b8b06868708050281860' ...
    '300072bdd95319f8c8a0004078283048f8d8401e2850a8e87858b84828783098d0f8' ...
    '4090e82050a8ffc878f08030b04018d8a8f89858d8582898fff096f0c828b48214ffb0' ...
    '40e86020a82818000000c8e0a890b070b8e0f8d0ecb0'], '%2x'), 3, [])' / 255;
[X, Y] = meshgrid(1:160, 1:144);
% The 160x144 screen is centred in the 4:3 window with square pixels
ax.XLim = [-15.5 176.5];
ax.YLim = [.5 144.5];
ax.YDir = 'reverse';
ax.Color = Cm(16, :);
% Pixel art is written as text: each letter is a palette colour, '.' = clear
L = zeros(1, 128);
L(double('kwgmnrRutbosdy')) = [2 1 3 4 5 6 7 8 9 10 11 12 13 15];
sp = @(s) L(double(s));
k2 = @(s) kron(sp(s), ones(2));
% (strings are read row by row: reshape(s, width, height)')
z.orb = k2(reshape('...kkkk.....kbbwwk...kbbbbwwk.oooooooooo.kbdbbbbk..kddbbbbk...kdddbk.....kkkk...', 10, 8)');
tb = '..kkkk...kooook.koowoook.kkkkkk.kbboobbksbbbbbbskbbbbbbk.kddddk.';
% Trainer: two walking frames (only the legs differ)
z.t = {k2(reshape([tb '.kd..k...kk.....'], 8, 10)'), k2(reshape([tb '..k..dk......kk.'], 8, 10)')};
% 8x8 tiles: 1 grass, 2 tall grass, 3 rock, 4 tree, 5 orb, 6 sparkle.
T = ['ggggggggggmggggggggggggggggggmgggggggggggmggggggggggggggggggggmg'
    'mmmmmmmmmmgmmmgmmgngmgnggnnngnnnmmmmmmmmmgmmmgmmgngmgngmnnngnnng'
    'ggggggggggkkkkgggkrrrRkgkrrrrRRkkrrRRRRkkRRRRRRkgkkkkkkggggggggg'
    'gkttttkgktmttmtkkttttttkktmtttmkgkttttkgggkuukggggkuukgggggggggg'
    'ggggggggggkkkkgggkbbwwkgoooooooogkdbbbkgggkkkkgggggggggggggggggg'
    'mmmmmmmmmymmmgmmmgngmynggnnngnnnmmmmmmmmmgmmmymmgngmgngmnnynnnng'];
TS = permute(reshape(sp(T)', 8, 8, 6), [2 1 3]);
% Battle scene: sky, field, two platforms, the trainer, text box, top bar
e = @(x, y, a, b) ((X - x) / a) .^ 2 + ((Y - y) / b) .^ 2 < 1;
B = 39 * ones(144, 160);
B(11:50, :) = 38;
B(e(110, 62, 36, 7) | e(40, 98, 30, 6)) = 37;
z.B0 = frame(stamp(B, z.t{1}, 78, 32));
% Distance from the creature's centre, used to draw the ring
z.D = hypot(X - 110, Y - 47);
% Creature names are 2-3 random 2-letter syllables from this string
z.sy = 'zumoribulonetavomikotufubaixresa';
% Per tier: name; then points, ring speed and base catch rate
z.TN = {'COMMON','UNCOMMON','RARE','EPIC','LEGENDARY'};
z.Q = [10 25 50 100 500; 2.4 3 3.8 4.6 5.6; .95 .85 .7 .55 .4];
% Tier odds: row 1 = tall grass, row 2 = sparkling grass
z.PR = [.6 .26 .1 .04 0; 0 .3 .35 .25 .1];
z.LB = {'OK...','NICE','GREAT!','PERFECT!'};
% Mode table: 1 title, 2 game over, 3 roam, 4 flash, 5 generate creature,
% 6 appear, 7 aim, 8 throw, 9 wobble, 10 broke free, 11 caught
z.F = {@ti, @ti, @wk, @fl, @gn, @ap, @am, @th, @wb, @br, @ca};
z.TS = TS;
% Graphics are created once here; ren only updates them.
% G(1) is the screen image (uint8 palette indices: 0 = first colour,
% 8x less data per frame than doubles), G(2:4) are the HUD,
% the message box text and the big label.
colormap(ax, Cm);
o = {'HitTest','off','PickableParts','none'};
z.G = gobjects(1, 4);
z.G(1) = image(ax, 'XData', [1 160], 'YData', [1 144], 'CData', zeros(144, 160, 'uint8'), o{:});
% Each row: x, y, font size, colour, alignment (1 left, 2 centre)
P = [4 2 .045 1 1; 10 112 .05 2 1; 80 30 .1 11 2];
A = {'left','center'};
for i = 1:3
    z.G(i + 1) = text(ax, P(i, 1), P(i, 2), '', o{:}, 'FontName', 'Courier New', 'FontWeight', 'bold', ...
        'FontUnits', 'normalized', 'FontSize', P(i, 3), 'Color', Cm(P(i, 4), :), ...
        'HorizontalAlignment', A{P(i, 5)}, 'VerticalAlignment', 'top');
end
[z.s, z.tt, z.ph, z.best, z.ob, z.sc, z.ct, z.C, z.h, z.m, z.b] = deal(1, 0, 0, 0, 3, 0, 0, ones(144, 160), '', '', '');
end

function z = upd(z, dt, k)
% Run the current mode; when the mode changes, restart its clock
n = z.s;
z.tt = z.tt + dt;
z.m = '';
z.b = '';
f = z.F{n};
z = f(z, dt, k);
z.tt = z.tt * (z.s == n);
z.ph = z.ph + 7 * rand * (z.s ~= n);
z.h = sprintf('ORBS %d  SCORE %d  HI %d', z.ob, z.sc, z.best);
end

function ren(~, z)
z.G(1).CData = uint8(z.C - 1);
set(z.G(2:4), {'String'}, {z.h; z.m; z.b});
end

function z = ti(z, ~, k)
% Title (mode 1) and game over (mode 2)
z.C = stamp(z.B0, z.orb, 46, 100);
z.b = 'CATCH RING';
z.m = sprintf('One button: SPACE or click.\nTap to turn, tap to throw.\nPress to start!');
if z.s == 2
    z.b = sprintf('SCORE %d', z.sc);
    z.m = sprintf('Out of orbs! %d caught.\n\nPress to play again.', z.ct);
end
if k && z.tt > .6
    % New route: tall-grass patches, rocks, orbs, sparkles, tree walls
    N = 2000;
    g = conv2(rand(N, 20), ones(5) / 25, 'same') > .52;
    R = rand(N, 20);
    M = 1 + g + 2 * (R < .015 & ~g);
    M(R > .994) = 5;
    M(g & R > .5 & R < .512) = 6;
    M(:, [1 20]) = 4;
    % Short clear start, then a grass patch and an orb straight ahead.
    % The last 20 rows copy the first 20 so the route loops seamlessly.
    M(15:20, 2:19) = 1;
    M(8:13, 7:14) = 2;
    M(11, 12) = 5;
    M(N-19:N, :) = M(1:20, :);
    [z.Mp, z.ob, z.sc, z.ct, z.lr, z.tx, z.dr, z.yv, z.me, z.sk, z.s] = ...
        deal(M, 3, 0, 0, -1, 72, 1, (N - 19) * 8, .6, 0, 3);
end
end

function z = wk(z, dt, k)
% Roam: tap flips direction; the trees at the edges bounce you back
z.dr = z.dr * (1 - 2 * k);
z.yv = z.yv - min(32 + 2 * z.ct, 70) * dt;
z.yv = z.yv + (z.yv < 8) * (size(z.Mp, 1) - 20) * 8;
z.tx = z.tx + z.dr * 55 * dt;
z.dr = sign(z.dr + 3 * (z.tx < 9) - 3 * (z.tx > 136));
z.tx = min(max(z.tx, 9), 136);
r = floor(z.yv / 8);
if r ~= z.lr
    % A new row is about to scroll in: add rocks, more as the score grows
    z.lr = r;
    z.Mp(r, 1 + find(z.Mp(r, 2:19) < 3 & rand(1, 18) < min(.015 + z.sc / 5000, .2))) = 3;
end
% Build the visible 19x20 tiles into one image in a single reshape
V = z.Mp(r + (1:19), :);
C = reshape(permute(reshape(z.TS(:, :, V), 8, 8, 19, 20), [1 3 2 4]), 152, 160);
C = C(mod(floor(z.yv), 8) + (1:144), :);
tr = z.t{1 + mod(floor(z.tt * 8), 2)};
C = stamp(C, tr(:, 8.5 + z.dr * (-7.5:7.5)), 100, round(z.tx));
% What is under the trainer's feet?
y = floor((z.yv + 115) / 8) + 1;
x = floor((z.tx + 6) / 8) + 1;
g = z.Mp(y, x);
% Rock (3) -> grass, orb (5) -> grass, sparkle (6) -> tall grass
z.Mp(y, x) = g - 2 * (g == 3) - 4 * (g > 4);
z.ob = max(z.ob - (g == 3) + (g == 5), 0);
z.sk = z.sk + .3 * (g == 3);
z.me = z.me + (g == 2) * dt * (.25 + .3 * rand);
z.bo = 1 + (g == 6);
% Next mode: flash into a battle, game over if out of orbs, else keep roaming
z.s = 3 + (g == 6 || z.me >= 1);
z.s = z.s - (z.s - 2) * (z.ob < 1);
% Screen shake after hitting a rock
C = circshift(C, (z.sk > 0) * (randi(5, 1, 2) - 3));
z.sk = max(z.sk - dt, 0);
z.Cw = C;
% Top bar with the encounter meter
C(1:10, :) = 16;
C(3:8, 118:157) = 2;
C(4:7, 119:118 + round(38 * min(z.me, 1))) = 15;
z.C = C;
end

function z = fl(z, ~, ~)
% Encounter transition: the screen blinks white, then goes dark
t = z.tt;
b = mod(floor(t * 10), 2) * (t < .5) + 2 * (t > .5);
z.C = z.Cw * ~b + b;
z.s = 4 + (t > .8);
end

function z = gn(z, ~, ~)
% Roll a tier and a shiny, then build the creature's sprite
t = find(rand < cumsum(z.PR(z.bo, :)), 1);
h = double(t < 5 && rand < 1 / 15);
if t > 4
    [S, n] = leg;
else
    [S, n] = mon(t, h, z.sy);
end
% Outline: dark blue for the legendary, black for everyone else
S(conv2(double(S > 0), ones(3), 'same') > 0 & S == 0) = 2 + 11 * (t > 4);
[z.cr, z.pts, z.tl, z.nm, z.tier, z.sh, z.w, z.bc, z.me, z.C, z.s] = ...
    deal(kron(S, ones(2)), z.Q(1, t) * (1 + 2 * h), 3, [repmat('SHINY ', 1, h) n], t, h, ...
    min(z.Q(2, t) + .08 * z.ct, 7), z.Q(3, t) - .1 * h, 0, z.B0, 6);
end

function [S, n] = mon(t, h, sy)
% Random symmetric creature: random left half, mirrored, with a solid core
% so it is never too small, then smoothed into a blob
[i, j] = ndgrid(1:14, 1:7);
q = rand(14, 7) < 1.1 + .04 * t - hypot((i - 8) / 7, (j - 7.5) / 6.5);
B = zeros(16);
B(2:15, 2:15) = [q fliplr(q)];
B(6:11, 6:11) = 1;
B = conv2(B, ones(3), 'same') >= 5;
B([1 16], :) = 0;
B(:, [1 16]) = 0;
% Tier colours (3 shades) or gold if shiny: body, symmetric spots, rim light
c = 14 + 3 * t + h * (15 - 3 * t);
q = rand(16, 8) < .2;
S = (c + 1) * B;
S(B & [q fliplr(q)]) = c + 2;
S(B & ~[false(1, 16); B(1:15, :)]) = c;
% Eyes inside the core, mirrored, with a white highlight above
r = randi([7 9]);
c = randi([7 8]);
S(r, [c 17-c]) = 2;
S(r - 1, [c 17-c]) = 1;
i = 2 * randi(16, 1, 2 + (rand < .4));
j = [i - 1; i];
n = upper(sy(j(:)'));
end

function [S, n] = leg
% MEMBRAX: shaded by the height of the L-shaped membrane's first mode
Z = abs(membrane(1, 7));
h = Z / max(Z(:));
S = zeros(16);
S(1:15, 1:15) = (h > .02) .* (34 - (h > .33) - (h > .66));
[~, i] = max(Z(:));
[a, c] = ind2sub([15 15], i);
S(a, [c-1 c+1]) = 2;
S(a - 1, [c-1 c+1]) = 1;
n = 'MEMBRAX';
end

function z = ap(z, ~, ~)
% A wild creature slides in from the right
t = z.tt;
z.C = stamp(z.B0, z.cr, 31, 94 + round(max(0, 1 - t / .5) * 70));
z.m = sprintf('A wild %s appeared!\n%s  %d pts', z.nm, z.TN{z.tier}, z.pts);
z.s = 6 + (t > 1.4);
end

function z = am(z, ~, k)
% The ring pulses; it turns orange when it's close to the smallest size
r = 19 + 17 * (.5 + .5 * cos(z.w * z.tt + z.ph));
q = 1 - (r - 19) / 17;
C = z.B0;
C(abs(z.D - r) < 1.3) = 13 - 2 * (q > .8);
z.C = stamp(C, z.cr, 31, 94);
z.m = sprintf('Tap when the ring is\nSMALLEST!  (%d tries left)', z.tl);
if k
    % Rate the timing, then pre-roll the 3 wobbles: n = wobbles survived
    z.lb = z.LB{1 + (q > .4) + (q > .7) + (q > .92)};
    n = find([rand(1, 3) >= (z.bc * (.15 + .85 * q ^ 2)) ^ (1 / 3), 1], 1) - 1;
    [z.nP, z.ob, z.tl, z.s] = deal(n, z.ob - 1, z.tl - 1, 8);
end
end

function z = th(z, ~, ~)
% The orb arcs from the trainer to the creature
u = min(z.tt / .45, 1);
C = stamp(z.B0, z.cr, 31, 94);
z.C = stamp(C, z.orb, round(72 - 33 * u - 40 * sin(pi * u)), round(38 + 62 * u));
z.b = z.lb;
z.m = sprintf('You threw a\ncapture orb!');
z.s = 8 + (z.tt > .45);
end

function z = wb(z, ~, ~)
% Wobble n times, then either caught (all 3) or broke free
n = z.nP;
u = z.tt - .3;
v = mod(u, .7);
z.C = stamp(z.B0, z.orb, 46, 100 + round(4 * sin(2 * pi * v / .4)) * (u > 0 && floor(u / .7) < n && v < .4));
z.b = z.lb(1:end * (z.tt < .6));
z.m = repmat('. ', 1, 1 + min(floor(max(u, 0) / .7), n));
if z.tt > .4 + .7 * n
    c = n == 3;
    [z.sc, z.ct, z.s] = deal(z.sc + c * z.pts, z.ct + c, 10 + c);
    z.best = max(z.best, z.sc);
end
end

function z = br(z, ~, ~)
% Broke free: the creature blinks back. Then retry; after the 3rd try it
% escapes and you keep roaming; with no orbs left it's game over.
t = z.tt;
z.C = stamp(z.B0, z.cr * (t > .4 || mod(floor(t * 10), 2)), 31, 94);
z.m = sprintf('Oh no! %s\nbroke free!', z.nm);
g = 7 - 4 * (z.tl < 1);
g = g - (g - 2) * (z.ob < 1);
z.s = 10 + (g - 10) * (t > 1.1);
end

function z = ca(z, ~, k)
% Caught! Tap to keep roaming (or see the score if out of orbs)
z.C = stamp(z.B0, z.orb, 46, 100);
z.m = sprintf('Gotcha! %s\nwas caught!  +%d pts', z.nm, z.pts);
z.s = 11 - (8 + (z.ob < 1)) * (z.tt > .6 && k);
end

function C = frame(C)
% Text box at the bottom and the dark bar at the top
C(106:142, 3:158) = 16;
C(108:140, 5:156) = 1;
C(1:10, :) = 16;
end

function C = stamp(C, S, r, c)
% Draw sprite S (0 = transparent) with its top-left corner at row r, col c
[I, J] = find(S);
i = I + r - 1;
j = J + c - 1;
v = i >= 1 & i <= size(C, 1) & j >= 1 & j <= size(C, 2);
C(sub2ind(size(C), i(v), j(v))) = S(sub2ind(size(S), I(v), J(v)));
end
Play Game
Preview

Play Game opens this in MATLAB Drive. Click Run this app there to play.