How BPTD Works? - Core Mechanics of BPTD

Hello, In our first blog post, we talked about what kind of game BPTD is, who is developing it, and the purpose of this devlog. In this post, we’ll focus on the game’s core mechanics. By the end, you’ll have a better idea of how BPTD plays at its most basic level.

Core Loop

The core loop of the game can be summarized as:
- Play Card
- Defend Base
- Upgrade Board

Each of these steps is divided into smaller phases:

Play Card phase;
- Buy grid card
- Buy unit/building card
- Place cards on the board

A unit or building card cannot be played without a grid card. These grid cards essentially form the player's "backpack" area.

Defend Base phase;
- Place the cards on the board
- Rearrange the cards into an optimized layout

Placing cards randomly leads to inefficient use of space and missed fusion/link opportunities. Because of that, optimizing the limited space becomes one of the player's top priorities.

Upgrade Board phase;
- Buy new and stronger cards from the shop,
- Fuse/link cards or level them up to strengthen your setup.

Placing Cards into the Backpack

In BPTD, the player’s main area of control is a limited grid-based board. This grid space becomes the player’s backpack. As mentioned in the core loop, every time a player wants to play a card, they must also play a grid card with enough space to hold it. Without a grid card, no unit or building card can be played.

Players build and upgrade their own backpack during the match. Just like unit/building cards, grid cards also come in various types depending on how many grid tiles they contain and the features they provide. We’ll go into more detail on those in a future post.

In short, where a card is placed determines what it will interact with, what abilities it will trigger, and how much of its potential can be used. Since the space is limited, each placement is a decision: Which card should be prioritized, and which one should be sacrificed?

Fusion and Link Mechanics

Some cards can be combined under certain conditions—this is what we call fusion. If the player places two fusion-compatible cards on adjacent grids, after one turn they merge into a new, stronger card.

On the other hand, some cards can interact without merging into a new card. These cards, when placed adjacent to each other, can share part or all of their power. We call this mechanic linking. Unlike fusion, linked cards do not combine, and the effect disappears if they’re moved apart.

These two systems push the player to think beyond individual cards and consider their relationships, creating deeper strategic choices.

Grid Movement

As mentioned in the fusion and link sections, positioning is not just about efficient space use. It also determines potential interactions between cards, which makes grid movement highly important.

Both grid and unit/building cards can be rotated in four directions. This lets players decide not only how they want to shape their board but also which way their cards will face. Sometimes, moving a card one tile to the right can create a new fusion opportunity. Other times, sliding a card away opens up space for something more powerful. These small adjustments allow for more planning without breaking the flow of the game.

Closing Thoughts

In this post, we tried to go over the core systems that make up BPTD. As always, feel free to reach out if you have any questions or feedback. Don't forget to follow us on other social media platforms.

See you in the next devlog!