Bullet Power Selection Strategy

Origins

Fire power selection strategies were developed and documented by the RoboWiki community, with notable contributions including Albert's power selection algorithm.

Choosing the right bullet power is one of the most consequential tactical decisions in Robocode. Fire is too weak, and you leave damage on the table; fire is too strong, and you waste energy on slow bullets that miss. This page presents a strategic framework for bullet power selection that adapts to distance, energy levels, targeting confidence, and battle context.

Bullet Power Decision Factors

The table below provides quick-reference guidelines for choosing bullet power based on four key factors. Colors indicate the recommended power level:

• 🟢 Green = High power (2.5–3.0) — Favorable conditions for heavy bullets
• 🟡 Yellow/Orange = Moderate power (1.0–2.5) — Balanced situations
• 🔴 Red = Low power (0.5–1.5) — Conservative fire required
• 🔵 Blue = Calculated power — Tactical situations requiring precise calculation
• ⚫ Gray = Context-dependent — Adjust based on the situation

Factor	Condition	Recommended Power	Rationale
Distance	Close (< 150 units)	2.5–3.0	Bullets arrive quickly; maximize damage
	Medium (150–400 units)	1.8–2.2	Balance damage with bullet speed
	Long (> 400 units)	0.8–1.5	Prioritize speed to reduce travel time
Your Energy	Critical (< 15)	0.5–1.0	Preserve energy; avoid disablement
	Low (15–35)	1.0–1.8	Balance offense with survival
	Healthy (35–70)	1.8–2.5	Standard combat flexibility
	Dominant (> 70)	2.5–3.0	Can afford heavy shots and pressure
Confidence	High (hit rate > 70%)	2.5–3.0	Landing shots; maximize damage
	Moderate (hit rate 40–70%)	1.8–2.2	Competitive performance
	Low (hit rate < 40%)	0.8–1.5	Prioritize speed over damage
Context	1v1 balanced	1.8–2.2	Accuracy matters most
	Melee standard	1.5–2.0	Energy efficiency priority
	Finishing shot	Calculate minimum	Don't waste power on overkill
	Enemy cornered	+0.3–0.5	Limited evasion options

Why bullet power is strategic

Bullet power selection directly impacts four combat dimensions:

1. Damage output — Higher power delivers more damage: $\text{damage} = 4 \times \text{power} + \max(0, 2 \times (\text{power} - 1))$
2. Bullet speed — Lower power travels faster: $\text{speed} = 20 - 3 \times \text{power}$ units/turn
3. Energy cost — Each shot costs energy equal to its power (0.1 to 3.0)
4. Gun cooldown — Higher power adds more heat: $\text{heat} = 1 + \frac{\text{power}}{5}$

These tradeoffs create a fundamental tension: high damage comes at the cost of speed, energy, and firing rate. The optimal choice depends on the tactical situation.

Scoring efficiency matters more than raw damage

A 1.5 power bullet that hits scores more points than a 3.0 power bullet that misses. Your goal is to maximize expected damage per shot, not theoretical maximum damage.

The strategic framework

Effective bullet power selection considers four primary factors:

Distance to target

Distance determines bullet travel time, which directly affects hit probability. Longer travel times amplify targeting errors and give opponents more time to evade.

Strategic guidelines:

• Close range (< 150 units): Use high power (2.5–3.0). Bullets arrive quickly regardless of speed, so maximize damage.
• Medium range (150–400 units): Use moderate power (1.8–2.2). Balance damage with reasonable bullet speed.
• Long range (> 400 units): Use low power (0.8–1.5). Prioritize speed to minimize prediction error and evasion time.

Rationale: At close range, the enemy cannot evade effectively, so slow bullets don't matter. At long range, even a perfect prediction can be missed if the bullet is too slow — the target has more time to change course or respond to battlefield events.

Energy levels

Your energy level determines how much risk you can afford. Low energy demands conservative play; high energy enables aggressive power selection.

Your energy state:

• Critical (< 15): Fire 0.5–1.0 power. Preserve energy to avoid disablement. One heavy bullet that misses could end the round.
• Low (15–35): Fire 1.0–1.8 power. Balance offense with survival. You can still fight, but you can't afford waste.
• Healthy (35–70): Fire 1.8–2.5 power. Standard combat power levels with flexibility.
• Dominant (> 70): Fire 2.5–3.0 power when justified. You can absorb the energy cost and sustain pressure.

Enemy energy state:

• Enemy critical (< 15): Use just enough power to finish them. Don't waste 3.0 when 1.5 will kill.
• Enemy low (15–35): Increase power to pressure them. Force defensive behavior.
• Energy advantage (you > enemy + 30): Use heavy bullets to press your advantage and force trades.

Rationale: Energy is survival. When low, every shot could be your last, so maximize shot count over per-shot damage. When high, you can afford to trade misses for knockout power.

Targeting confidence

If your bot tracks hit rates or prediction confidence, use that data to adjust power. High confidence justifies high power; low confidence demands speed over damage.

Confidence-based scaling:

• High confidence (hit rate > 70%): Fire 2.5–3.0 power. You're landing shots — maximize damage.
• Moderate confidence (hit rate 40–70%): Fire 1.8–2.2 power. You're competitive but not dominant.
• Low confidence (hit rate < 40%): Fire 0.8–1.5 power. Prioritize bullet speed to increase hit probability.

Implementation note: Many advanced bots use virtual guns or statistical targeting systems that provide confidence metrics. If you don't track confidence, fall back to distance and energy-based decisions.

Rationale: A 3.0 power bullet that hits is worth more than a 1.0 power bullet, but a 1.0 power bullet that hits is worth infinitely more than a 3.0 power bullet that misses. If you're struggling to hit, faster bullets improve your odds.

Battle context adjustments

Beyond distance, energy, and confidence, certain tactical situations call for specific power choices:

Finishing shots

When the enemy is low on energy and one shot can win the round, calculate the minimum power needed. Recall the damage formula: $\text{damage} = 4 \times \text{power} + \max(0, 2 \times (\text{power} - 1))$

Work backwards: if you know the enemy's remaining energy, find the minimum power to exceed it:

$\text{power} \approx \frac{\text{enemyEnergy}}{6}$ (for power > 1.0, accounting for the bonus term)

For lower powers (0.1–1.0), use the simpler formula:

$\text{power} \approx \frac{\text{enemyEnergy}}{4}$

Example: Enemy has 8 energy remaining.

• Using the general formula: $\text{power} \approx \frac{8}{6} \approx 1.33$
• A 1.5 power bullet deals $4 \times 1.5 + 2 \times (1.5 - 1) = 6 + 1 = 7$ damage (not quite enough)
• A 2.0 power bullet deals $4 \times 2.0 + 2 \times (2.0 - 1) = 8 + 2 = 10$ damage (kills them)
• Fire 2.0 power.

Key principle: Always round up and add a small buffer to account for floating-point rounding. Firing 3.0 when 1.5 will do is wasteful — aim for the minimum that guarantees the kill, no more.

Melee combat

In melee battles (3+ bots), bullet power selection requires different priorities:

• Conservative by default: Fire 1.5–2.0 power to balance damage with energy efficiency. You're fighting multiple opponents, so energy conservation matters more than 1v1.
• Opportunistic heavy shots: Use 2.5–3.0 power only when you have a high-confidence shot at a low-energy bot you can eliminate.
• Light shots when crowded: If multiple bots are clustered or moving unpredictably, fire 0.8–1.2 power to increase hit probability.

Rationale: Melee rewards consistent scoring over knockout power. Eliminating bots earns survival points, but wasting energy on missed heavy bullets leaves you vulnerable to focused fire.

Wall proximity

When the enemy is near a wall, their evasion options are limited. This is an opportunity for higher power:

• If they're cornered (< 100 units from wall), consider 2.5–3.0 power even at longer distances.
• If they're approaching a wall predictably, fire heavier than distance alone would suggest.

Rationale: Walls constrain movement, reducing the enemy's ability to dodge. This effectively increases your confidence, justifying higher power.

Common strategies in practice

Fixed power approach

Some competitive bots use a single fixed power (e.g., 1.95 or 2.0) for simplicity and consistency. This works well when:

• Your targeting system is highly accurate across distances.
• You want predictable gun heat cycles.
• You're optimizing for specific opponent types or battle conditions.

Pros: Simple, debuggable, consistent cooldown timing.
Cons: Ignores situational advantages (close range, energy imbalances, finishing shots).

Hybrid formula

Many advanced bots combine multiple factors into a single calculation:

basePower = 2.0

# Adjust for distance
if distance < 150:
    distanceFactor = 1.5
else if distance < 400:
    distanceFactor = 1.0
else:
    distanceFactor = 0.6

# Adjust for energy
myEnergy = getEnergy()
if myEnergy < 15:
    energyFactor = 0.3
else if myEnergy < 35:
    energyFactor = 0.7
else:
    energyFactor = 1.0

# Adjust for confidence (if tracked)
if hitRate > 0.7:
    confidenceFactor = 1.2
else if hitRate < 0.4:
    confidenceFactor = 0.6
else:
    confidenceFactor = 1.0

# Calculate final power
power = basePower * distanceFactor * energyFactor * confidenceFactor
power = clamp(power, 0.1, 3.0)

This approach dynamically scales power based on real-time conditions, adapting to each shot.

Tips and common mistakes

Don't waste energy on impossible shots

If your targeting system is struggling (hit rate < 30%) at long range, firing 3.0 power bullets is a guaranteed path to defeat. Drop to 1.0 or lower and focus on improving your aim before scaling up power.

Minimum viable power for finishing shots

When the enemy is low on energy, calculate the exact power needed to finish them. Firing 3.0 when 1.5 will do wastes energy and cooling time for your next target.

Common mistakes to avoid:

• Always firing maximum power: Slow bullets miss more often at long range. You score more damage with moderate power and higher hit rates.
• Ignoring your own energy level: Firing 3.0 power bullets when you have 12 energy is dangerous. One miss and you're disabled.
• Not adapting to melee: 1v1 strategies don't work in melee. Energy efficiency and survival matter more than knockout power.
• Forgetting gun heat: High power adds more heat. If you need to fire again quickly (e.g., finishing a wounded bot), moderate power reduces cooldown.

Summary

Bullet power selection is a multi-dimensional strategic problem. The optimal choice depends on:

• Distance: Closer targets justify higher power.
• Energy: Low energy demands conservative power.
• Confidence: High hit rates justify heavy bullets.
• Context: Finishing shots, melee battles, and wall proximity all influence decisions.

Competitive bots often use hybrid formulas that weigh these factors dynamically, adapting to each shot. Start with distance and energy-based rules, then add confidence tracking as your targeting system matures. Over time, you'll develop intuition for power selection that matches your bot's strengths and your opponents' weaknesses.

Next steps:

• Read Energy as a Resource for deeper energy management principles.
• See Fire Power & Timing Decisions for targeting-focused power considerations.
• Explore Bullet Travel & Bullet Physics for the underlying mechanics.

Further Reading

• Selecting Fire Power — RoboWiki (classic Robocode)
• Bullet — RoboWiki (classic Robocode)