Crystal Bastion

Place glowing crystal towers on a dark grid to stop 20 waves of enemies from reaching your exit — a tight, satisfying tower defense in vanilla canvas.

Date: 2026-06-24 Genre: tower defense Status: Playable build

Concept

Crystal Bastion drops the player onto a 22×13 grid bisected by a winding S-curve path. Enemies spawn off the left edge and race toward the right exit; the player spends gold to build crystal towers on non-path cells to destroy them before they escape. The fantasy angle is elemental crystal energy — towers fire beams, lob cannonballs, freeze enemies, and ignite them. The aesthetic is neon-on-dark with glowing gem crystals and particle bursts, creating a space-dungeon feel without any external assets.

How to play

Stop enemies from reaching the exit (right edge). Each enemy that escapes costs one life — lose all 20 and it is game over. Kill enemies to earn gold, spend gold to place towers on empty grid cells. Press Space (or the Wave button) to send the next wave manually. Survive all 20 waves to win.

Keys: 1–4 select tower type · click grid to place · click a placed tower to inspect/sell (click it again to confirm sell at 60% refund) · Space start wave · R restart.

Touch: tap a tower button in the HUD, then tap a grid cell. Tap a placed tower once to show sell price, again to confirm.

Core mechanics

• Grid-based placement — 22×13 tile map; path cells are forbidden; all other cells are buildable.
• Four tower archetypes — Bolt (fast single-target beam), Cannon (slow AoE cannonball), Frost (slows targets 62%), Inferno (damage-over-time burn aura).
• Enemy priority targeting — towers always shoot the enemy farthest along the path within range, preventing bleed-through.
• Sell system — any placed tower refunds 60% of its cost; rewards adaptive play over set-and-forget.
• Wave spawning queue — each wave fires staggered spawn groups with per-group delays, producing mixed enemy compositions rather than single-type blobs.

Progression & scoring

Twenty waves escalate in three phases: early waves are Scout rushes (fast, fragile); mid waves introduce Troopers and Tanks (tougher, armored); late waves mix Speeders with Tank columns and occasional Titan boss enemies (wave 15 and 20). Enemy HP scales by 7% per wave. Score = enemy gold value × 10 per kill; there is no combo multiplier, just raw throughput. Surviving a wave without losing lives is not rewarded with gold — pressure is maintained throughout.

Look & feel

Dark grid on a near-black background (#0a0a1e) with cyan/blue grid lines. The path is a warm dark-amber strip with dashed center-lane markings. Towers are hexagonal crystal gems with shadowBlur glow in their elemental color (electric blue, orange-fire, icy cyan, inferno red). Enemies are colored glowing circles with health bars. Death events spawn radial particle bursts in the enemy's color. Projectiles are either glowing cannonballs or brief beam-lines that fade out in 130ms. Audio is omitted — the visual feedback (glow, particles, burst) carries the impact.

What makes it fun

• Path S-curve with three straights gives 6–7 meaningful tower slots that can cover overlapping segments, rewarding spatial thinking.
• Frost + Cannon combo — freezing enemies lets Cannon shells land reliably in the cluster, creating an emergent synergy without explicit combo rules.
• Armored enemies penalize cheap burst strategies — Tanks and Titans have 20–30% armor, making Inferno burn over-time better than raw Cannon spam by the mid-game.
• Manual wave timing — players control when each wave launches, letting them save gold for upgrades and pre-position before pressure arrives.