Skills yoink

Play Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder, check game stats and leaderboards, view player scores, and compete for the trophy. Uses Bankr for transaction execution.

install

source · Clone the upstream repo

git clone https://github.com/BankrBot/skills

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/BankrBot/skills "$T" && mkdir -p ~/.claude/skills && cp -r "$T/yoink" ~/.claude/skills/bankrbot-skills-yoink && rm -rf "$T"

manifest: yoink/SKILL.md

source content

Yoink

Play Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder to start your clock. The player with the most total yoinks holds the trophy.

Contract:

0x4bBFD120d9f352A0BEd7a014bd67913a2007a878

on Base (chain ID 8453)

Game Rules

Yoink the flag - Call
```
yoink()
```
to take the flag from the current holder
Cooldown - You must wait 10 minutes (600 seconds) between yoinks
No self-yoink - You cannot yoink from yourself
Accumulate time - While you hold the flag, your time score increases
Compete for trophy - The player with the most total yoinks holds the trophy (token ID 2)
Track yoinks - Your total yoink count is tracked separately from time

Contract Interface

RPC template:

curl -s -X POST https://mainnet.base.org -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x4bBFD120d9f352A0BEd7a014bd67913a2007a878","data":"SELECTOR+PARAMS"},"latest"],"id":1}' | jq -r '.result'

Function	Selector	Params	Returns
`yoink()`	`0x9846cd9e`	-	(write)
`lastYoinkedBy()`	`0xd4dbf9f4`	-	address
`lastYoinkedAt()`	`0x6a99616f`	-	uint256 timestamp
`totalYoinks()`	`0xa5d0dadd`	-	uint256
`topYoinker()`	`0x6a974e6e`	-	address (trophy holder)
`mostYoinks()`	`0xd2d7774a`	-	uint256 (record)
`COOLDOWN()`	`0xa2724a4d`	-	uint256 (600)
`score(address)`	`0x776f3843`	addr (32B padded)	(yoinks, time, lastYoinkedAt)
`balanceOf(address,uint256)`	`0x00fdd58e`	addr + tokenId	uint256 (FLAG_ID=1, TROPHY_ID=2)

Encoding: Addresses are zero-padded to 32 bytes.

score()

returns 96 bytes (3 × uint256).

Yoinking

Use Bankr's arbitrary transaction feature:

{
  "to": "0x4bBFD120d9f352A0BEd7a014bd67913a2007a878",
  "data": "0x9846cd9e",
  "value": "0",
  "chainId": 8453
}

Errors

Error	Selector	Meaning
`SlowDown(uint256)`	`0x58d6f4c6`	Cooldown not elapsed. Param = seconds remaining.
`Unauthorized()`	`0x82b42900`	You already hold the flag.

Cooldown check:

current_time - lastYoinkedAt() >= 600

Workflow

Query
```
lastYoinkedBy()
```
and
```
lastYoinkedAt()
```
to check status/cooldown
Ensure cooldown elapsed (600s) and you're not current holder
Submit yoink transaction via Bankr
Verify with
```
lastYoinkedBy()
```
or
```
score(address)
```

Resources

Basescan: https://basescan.org/address/0x4bBFD120d9f352A0BEd7a014bd67913a2007a878 (ABI, events, source)
Source Code: https://github.com/horsefacts/yoink-contracts