FXGL Roguelike / Roguelite
Save Architecture: Two Files
// Run save (wiped on death) — stored in "run_save"
// Meta save (permanent) — stored in "meta_save"
// Never mix them. On death:
// 1. Update meta save with run stats
// 2. Delete/reset run save
// 3. Show death screen, offer return to main menu
Run Initialization
@Override
protected void initGameVars(Map<String, Object> vars) {
// Run-scoped (reset on death)
vars.put("floor", 1);
vars.put("gold", 0);
vars.put("kills", 0);
vars.put("runScore", 0);
vars.put("playerHP", 100);
vars.put("playerMaxHP", 100);
vars.put("playerATK", 10);
vars.put("playerDEF", 0);
// Run item flags
vars.put("hasFireSword", false);
vars.put("hasIceShield", false);
vars.put("hasVampirism", false);
}
private void startNewRun() {
// Reset all run-scoped variables to defaults
initGameVars(new HashMap<>()); // conceptually — in practice re-init the game
set("runSeed", System.currentTimeMillis());
generateFloor(geti("floor"));
}
Procedural Floor Generation
private long runSeed;
private void generateFloor(int floorNumber) {
// Clear existing entities
getGameWorld().getEntitiesCopy().forEach(Entity::removeFromWorld);
// Seed per-floor: deterministic from run seed + floor
long floorSeed = runSeed + floorNumber * 7919L;
DungeonConfig config = new DungeonConfig()
.gridWidth(40 + floorNumber * 2)
.gridHeight(40 + floorNumber * 2)
.minRoomSize(4)
.maxRoomSize(10 + floorNumber)
.maxRooms(8 + floorNumber * 2)
.seed(floorSeed);
DungeonGenerator gen = new DungeonGenerator(config);
Grid2D<DungeonCell> dungeon = gen.generate();
spawnDungeonTiles(dungeon);
placeEntities(gen.getRooms(), floorNumber);
// Rebuild A* grid after level load
astarGrid = AStarGrid.fromWorld(getGameWorld(), TILE, TILE);
}
private void placeEntities(List<Room> rooms, int floor) {
Random rng = new Random(runSeed + floor * 13L);
// Player starts in room 0
Room start = rooms.get(0);
player.setPosition(start.getCenterX() * TILE, start.getCenterY() * TILE);
// Boss in last room
Room boss = rooms.get(rooms.size() - 1);
spawn("boss_" + getBossTypeForFloor(floor),
boss.getCenterX() * TILE, boss.getCenterY() * TILE);
// Enemies and items in middle rooms
for (int i = 1; i < rooms.size() - 1; i++) {
Room room = rooms.get(i);
int enemyCount = rng.nextInt(3) + 1 + floor / 2;
for (int e = 0; e < enemyCount; e++) {
spawn("enemy_" + getRandomEnemyType(floor, rng),
room.getX() * TILE + rng.nextInt(room.getWidth()) * TILE,
room.getY() * TILE + rng.nextInt(room.getHeight()) * TILE);
}
// 30% chance for a chest
if (rng.nextDouble() < 0.3) {
spawn("chest", room.getCenterX() * TILE, room.getCenterY() * TILE);
}
}
// Stairs to next floor in boss room (unlock after boss dies)
spawn("stairs_locked", boss.getCenterX() * TILE + TILE, boss.getCenterY() * TILE);
}
Weighted Loot Table
public record LootEntry(String itemId, int weight, Rarity rarity) {}
// Rarity system with weights
public enum Rarity { COMMON(60), UNCOMMON(25), RARE(12), LEGENDARY(3);
public final int baseWeight;
Rarity(int w) { this.baseWeight = w; }
}
private final List<LootEntry> lootTable = List.of(
new LootEntry("health_potion", 50, Rarity.COMMON),
new LootEntry("sword_iron", 30, Rarity.COMMON),
new LootEntry("shield_wood", 25, Rarity.COMMON),
new LootEntry("sword_fire", 15, Rarity.UNCOMMON),
new LootEntry("boots_speed", 12, Rarity.UNCOMMON),
new LootEntry("vampire_ring", 8, Rarity.RARE),
new LootEntry("mirror_shield", 5, Rarity.RARE),
new LootEntry("dragon_heart", 2, Rarity.LEGENDARY),
new LootEntry("time_stop_watch", 1, Rarity.LEGENDARY)
);
public String rollLoot(Random rng, int luckBonus) {
int totalWeight = lootTable.stream().mapToInt(e -> e.weight() + luckBonus).sum();
int roll = rng.nextInt(totalWeight);
int cumulative = 0;
for (LootEntry entry : lootTable) {
cumulative += entry.weight() + luckBonus;
if (roll < cumulative) return entry.itemId();
}
return lootTable.get(0).itemId(); // fallback
}
Item Offer Screen (Choose 1 of 3)
private void showItemOffer() {
Random rng = new Random();
String[] offers = {
rollLoot(rng, getLuckBonus()),
rollLoot(rng, getLuckBonus()),
rollLoot(rng, getLuckBonus())
};
// Ensure no duplicates
Set<String> unique = new HashSet<>();
for (int i = 0; i < offers.length; i++) {
while (!unique.add(offers[i])) offers[i] = rollLoot(rng, getLuckBonus());
}
getSceneService().pushSubScene(new ItemOfferSubScene(offers, this::applyItem));
}
public class ItemOfferSubScene extends GameSubScene {
private final String[] offers;
private final Consumer<String> onPick;
@Override
public void onOpen() {
HBox cards = new HBox(20);
for (String itemId : offers) {
ItemData item = getItemData(itemId);
VBox card = createItemCard(item);
card.setOnMouseClicked(e -> {
onPick.accept(itemId);
getSceneService().popSubScene();
});
cards.getChildren().add(card);
}
getRoot().getChildren().add(new VBox(20,
new Label("Choose an Item"),
cards
));
}
}
Item Synergy System
// Items check for other items to modify their behavior
public void applyItem(String itemId) {
switch (itemId) {
case "sword_fire" -> {
set("hasFireSword", true);
inc("playerATK", 5);
// Synergy: fire sword + ice shield = steam explosion on hit
if (getb("hasIceShield")) {
set("hasSteamExplosion", true);
showSynergyMessage("Fire + Ice = Steam Explosion!");
}
}
case "ice_shield" -> {
set("hasIceShield", true);
inc("playerDEF", 8);
if (getb("hasFireSword")) {
set("hasSteamExplosion", true);
showSynergyMessage("Fire + Ice = Steam Explosion!");
}
}
case "vampire_ring" -> {
set("hasVampirism", true);
// Vampirism lifesteal is handled in combat damage resolution
}
case "cursed_blade" -> {
// Curse: high damage but player takes 10% damage each floor
set("hasCursedBlade", true);
inc("playerATK", 20);
set("curseDamagePerFloor", 10);
showCurseWarning("Cursed Blade accepted. You will suffer for its power.");
}
}
}
// In combat damage resolution:
private void onPlayerDealsHit(int damage) {
if (getb("hasVampirism")) {
int heal = Math.max(1, damage / 5);
inc("playerHP", heal);
set("playerHP", Math.min(geti("playerHP"), geti("playerMaxHP")));
}
if (getb("hasSteamExplosion")) {
// Splash damage to nearby enemies
spawnExplosion(player.getCenter(), 80, damage / 2);
}
}
Permadeath and Run End
private void onPlayerDeath() {
getGameController().pauseEngine();
// Record run stats to permanent meta save
saveRunStats();
checkMetaUnlocks();
// Show death screen
getDialogService().showMessageBox(
"You died on floor " + geti("floor") + "\n" +
"Kills: " + geti("kills") + " | Gold: " + geti("gold"),
() -> returnToMainMenu()
);
}
private void saveRunStats() {
// Load existing meta save or create new
getSaveLoadService().load("meta_save");
// Update lifetime stats
inc("totalKills", geti("kills"));
inc("totalGold", geti("gold"));
inc("totalRuns", 1);
inc("metaCurrency", geti("floor") * geti("kills"));
int deepest = Math.max(geti("deepestFloor"), geti("floor"));
set("deepestFloor", deepest);
getSaveLoadService().saveAndForget("meta_save");
}
private void checkMetaUnlocks() {
if (geti("totalKills") >= 100 && !getb("unlocked_knight")) {
set("unlocked_knight", true);
showUnlockMessage("New character unlocked: The Knight!");
}
}
Floor Descent
// Player steps on stairs:
onCollisionBegin(EntityType.PLAYER, EntityType.STAIRS, (player, stairs) -> {
if (stairs.getString("state").equals("locked")) return;
inc("floor", 1);
play("sounds/stairs.wav");
generateFloor(geti("floor"));
});
// Unlock stairs when boss dies:
private void onBossDeath(Entity boss) {
getGameWorld().getEntitiesByType(EntityType.STAIRS_LOCKED)
.forEach(e -> { e.set("state", "unlocked"); /* update view */ });
inc("kills", 1);
spawnLoot(boss.getCenter(), 3); // boss drops 3 items
showItemOffer();
}
Gotchas
- Two separate save files — run state and meta state must never be in the same
DataFile.
Losing a run should never affect meta unlocks, and vice versa. Keep them strictly separated.
- Floor seed derived from run seed + floor number — this lets the player return to the
exact same floor layout if they die and replay (for debugging), while still making each run unique.
- Item offer RNG must be seeded independently — if item offers use the same RNG as floor
generation, opening the offer at different times gives different items. Seed item RNG with
(runSeed + floor * 13L) for consistent per-floor offers.
- Synergy detection runs at item pickup time — don't check synergies on every frame.
Check when a new item is applied and set a boolean flag. Combat code reads the flag.
getGameWorld().getEntitiesCopy() when clearing between floors — getEntities() returns
a live list; removing from it while iterating throws ConcurrentModificationException.- Cursor/Blessed items affect loot table weight — if items give "+luck", apply that bonus
to all weights in the loot table roll. Don't increase drop chance only for rare items.
- Permadeath save cleanup — after death, explicitly call
getSaveLoadService().deleteSave("run_save")
so a game crash can't leave a corrupted run save that bypasses permadeath.
JohannesRabauer