Games (also called competitions or events) are time-bound CTF competitions where teams compete to solve challenges and earn points.
Game Lifecycle
A game in GZCTF progresses through several states:
Game States
Before Start
Teams can register, but challenges are not accessible. Administrators can configure challenges and settings.
Active
The competition is live. Teams can access challenges, submit flags, and earn points. The game is considered active when:StartTimeUtc <= DateTimeOffset.Now && DateTimeOffset.Now <= EndTimeUtc
Ended
Competition time has expired. Depending on configuration:
- Practice Mode Enabled: Teams can still solve challenges (no scoring/ranking changes)
- Practice Mode Disabled: Challenges become inaccessible
Writeup Submission
If writeups are required, teams must submit before the writeup deadline.
Game Configuration
| Property | Description |
|---|
| Title | Game name displayed to participants |
| Summary | Brief description shown in game listings |
| Content | Detailed introduction with rules and information |
| PosterHash | Game poster image |
| Hidden | Hide game from public listings |
Timing
All times use UTC with DateTimeOffset for timezone accuracy.
public DateTimeOffset StartTimeUtc { get; set; }
public DateTimeOffset EndTimeUtc { get; set; }
public DateTimeOffset WriteupDeadline { get; set; }
Participation Settings
Team Registration
Open Registration
Review Required
Invite Only
AcceptWithoutReview = true
AcceptWithoutReview = false
InviteCode = "secret-code-2024"
// Limit team size (0 = no limit)
public int TeamMemberCountLimit { get; set; }
// Limit simultaneous containers per team
public int ContainerCountLimit { get; set; } = 3;
Writeup Configuration
Writeups are post-competition technical reports where teams explain their solutions.
public bool WriteupRequired { get; set; }
public DateTimeOffset WriteupDeadline { get; set; }
public string WriteupNote { get; set; } // Instructions for participants
WriteupRequired is true:
- Teams must submit writeups before the deadline
- Writeups can be reviewed and downloaded by administrators
- Teams without writeups may have different participation status
Scoring Configuration
Blood Bonuses
The first three teams to solve each challenge receive bonus points:
public BloodBonus BloodBonus { get; set; }
// Default values:
// First blood: +50% (1.5x multiplier)
// Second blood: +30% (1.3x multiplier)
// Third blood: +10% (1.1x multiplier)
Blood bonus percentages are stored as integers (parts per thousand) for precision:
- 50 = 5.0% bonus
- 300 = 30.0% bonus
- 500 = 50.0% bonus
long value:
BloodBonusValue = (FirstBlood << 20) + (SecondBlood << 10) + ThirdBlood
DefaultValue = (50 << 20) + (30 << 10) + 10 // 50%, 30%, 10%
Dynamic Scoring
See Scoring for detailed information about the dynamic scoring formula.
Security Features
Team Tokens
Each team participation generates a unique signed token:
public string PublicKey { get; set; } // Ed25519 public key
public string PrivateKey { get; set; } // Ed25519 private key (encrypted)
- Dynamic flag generation
- Team-specific challenge instances
- Preventing flag sharing detection
Team Hash Salt
A game-specific salt ensures flag uniqueness:
public string TeamHashSalt => $"GZCTF@{PrivateKey}@PK".ToSHA256String();
Practice Mode
Practice mode allows most operations to continue after the game ends, but rankings and scoring are frozen.
public bool PracticeMode { get; set; } = true;
- Challenges remain accessible after
EndTimeUtc
- Teams can still solve challenges
- Scores and rankings are not updated
- New teams cannot join
- Useful for learning and practicing
Divisions
Games can be divided into separate divisions (tracks) for different participant groups:
public HashSet<Division>? Divisions { get; set; }
- Separate scoreboards per division
- Different challenge visibility per division
- Division-specific permissions and invite codes
See Teams for more details.
Game Model Reference
The Game model is located at:
~/workspace/source/src/GZCTF/Models/Data/Game.cs
View Game Model Structure
public partial class Game
{
public int Id { get; set; }
public string Title { get; set; }
public string Summary { get; set; }
public string Content { get; set; }
public string? PosterHash { get; set; }
public bool Hidden { get; set; }
// Timing
public DateTimeOffset StartTimeUtc { get; set; }
public DateTimeOffset EndTimeUtc { get; set; }
public DateTimeOffset WriteupDeadline { get; set; }
// Configuration
public bool PracticeMode { get; set; } = true;
public bool AcceptWithoutReview { get; set; }
public bool WriteupRequired { get; set; }
public string? InviteCode { get; set; }
public int TeamMemberCountLimit { get; set; }
public int ContainerCountLimit { get; set; } = 3;
// Scoring
public BloodBonus BloodBonus { get; set; }
// Security
public string PublicKey { get; set; }
public string PrivateKey { get; set; }
// Relationships
public HashSet<GameChallenge> Challenges { get; set; }
public HashSet<Participation> Participations { get; set; }
public HashSet<Team>? Teams { get; set; }
public HashSet<Division>? Divisions { get; set; }
public List<GameEvent> GameEvents { get; set; }
public List<GameNotice> GameNotices { get; set; }
public List<Submission> Submissions { get; set; }
}
Challenges
Learn about challenge types and configuration
Teams & Participation
Understand how teams join and participate
Scoring System
Explore dynamic scoring and blood bonuses
Containers
Manage container-based challenges