D100 Diamond Engine — Roll Your Own 2025 MLB Season

One Die. One Season. One Story.

The D100 Diamond Engine is a solo tabletop baseball simulator built around a single core mechanic: roll d100 for each team, apply a modifier based on real team strength, read the result. That's it. No spreadsheets to maintain. No complicated charts to cross-reference. Just dice, a schedule, and 162 games to play.

It covers the full 2025 MLB season — all 2,430 games across 30 teams, from Opening Day in Tokyo through to the final week of September. Every game is there. Every series, every rivalry, every divisional grind.

How It Works

Each team rolls a d100. That roll gets modified by a pre-calculated MOD — a number derived from the team's offensive and defensive ratings, and whether they're playing at home. A stronger team on a hot streak at home gets a higher MOD. A depleted road side gets a lower one.

The raw roll plus the MOD maps to a run total on the scoring table. Roll a natural 1 and your offence collapses to zero. Roll a natural 100 and you trigger an explosion — bonus runs, chaos, the kind of game that ends up in the highlight reel.

For a little extra variance, each team also rolls a Star Die — a d6 that can add bonus runs on a 5 or 6. And if the game ends in a tie? Break out the d20 for extra innings.

What's in the App

The simulator lives in a single HTML file — no installation, no account, no internet required after the first load. Open it, start rolling.

Key features:

• Full 2025 schedule — 2,430 games in chronological order, day-by-day navigation
• Live standings — updates as you play, with GB, win percentage, run differential, and streaks
• Rankings tab — pre-season ratings alongside your live replay results
• Postseason picture — division leaders and wild card races update in real time as the season progresses
• Game recaps — write a short note on any game and it saves with the result
• CSV export and import — save your season, come back later, pick up exactly where you left off
• PDF standings export — print your standings at any point in the season

From the Opening Series — Tokyo, March 18–19

The 2025 season opened on neutral ground at the Tokyo Dome, Cubs vs Dodgers. No home field advantage for either side.

Game 1 was a statement. The Cubs came out sharp, built a lead early, and never let up. Final: Cubs 9, Dodgers 2. Los Angeles never found their rhythm.

Game 2 was everything Game 1 wasn't. The Dodgers came back with purpose, the Cubs held a 2–1 lead late — and then extras. The d20 hit the table. Cubs couldn't push one through. The Dodgers did. Walk-off, 3–2.

Series split. Both teams heading home with something to prove. That's the D100 Diamond Engine — two dice rolls and you've already got a story.

Play It on TTX Sports

The D100 Diamond Engine is free to use and available now on TTX Sports. Load it up, pick a starting date, and roll your season.

Play the D100 Diamond Engine →

If you play through a notable series or finish a full season, drop a comment or reach out — I'd love to see how your 2025 unfolds.