Sponsored Loot Drops
Distribute in-game rewards directly to players' wallets without any gas fees.
Privy social + sponsored tx· wallet UX
Section · Onchain
full primer →The primitive.
Game designers sign in with Google through Privy — no seed phrase, no MetaMask popup — and their reward distribution actions post to Linea Sepolia, where gas is sub-cent so the approval sheet flashes and disappears.
Why this primitiveSponsored transactions allow frictionless token drops without user gas payments, improving user experience.
Kernel
Privy embedded wallet bootstrapped with PRIVY_APP_ID — Google sign-in with a Linea Sepolia embedded wallet auto-provisioned for every user
Drives the UI as
a one-click 'Sign in with Google' that drops the user straight into the app with an onchain identity
Required keys.
LINEA_SEPOLIA_RPC_URL
Alchemy Linea Sepolia HTTPS endpoint. Create a free app → copy the HTTPS URL.
open ↗Add these in your Lovable project under Settings → Secrets before pasting the prompt below.
Appendix · Mega-prompt
The build prompt.
budget · 1 message
Paste into a fresh Lovable project. Make sure all five secrets above are set first. read the build strategy →
Build "Sponsored Loot Drops" in ONE Lovable message. Single-page demo.
CONCEPT
Distribute in-game rewards directly to players' wallets without any gas fees.
Discipline: Game Design & Interactive Media (reward distribution).
Onchain primitive: Privy social + sponsored tx. Why this primitive: Sponsored transactions allow frictionless token drops without user gas payments, improving user experience.
5-CREDIT BUDGET (HARD LIMIT):
- ONE single-page app. No router, no Lovable Cloud, no database, no auth flows beyond Privy drop-in.
- ONE Solidity contract, <=80 lines, deployed to Linea Sepolia, verified on LineaScan.
- Privy is always the auth layer (Google login, embedded wallet). Users pay their own gas — Linea Sepolia gas is negligible (sub-cent), so no paymaster or sponsorship is needed.
- Pinata/IPFS only if the idea genuinely needs to store a file or metadata.
- At most ONE AI call per user action (use Lovable AI Gateway with LOVABLE_API_KEY if AI is part of the idea).
- Skip tests, skip CI, skip docs pages. Ship the demo, nothing else.
STACK
- React + Vite single page (the index route).
- SSR-safe Privy mount is mandatory. Never import @privy-io/react-auth at
module scope of a route file — it crashes SSR. Use
lazy(() => import('./privy-client-entry')) inside <ClientOnly> + <Suspense>,
and put <PrivyProvider> only inside privy-client-entry.tsx.
- PrivyProvider config MUST declare Linea Sepolia as the default AND only
supported chain — otherwise Privy defaults to Ethereum mainnet, refuses
switchChain(59141) silently, and sendTransaction hangs forever with the
button stuck on "Logging on chain…". Import lineaSepolia from viem/chains:
import { lineaSepolia } from 'viem/chains';
<PrivyProvider appId={import.meta.env.VITE_PRIVY_APP_ID}
config={{ loginMethods:['google','email'],
embeddedWallets:{ ethereum:{ createOnLogin:'users-without-wallets' } },
appearance:{ theme:'dark' },
defaultChain: lineaSepolia,
supportedChains: [lineaSepolia] }}>
- Read the embedded wallet from useWallets, not user.wallet:
const embedded = wallets.find(w => w.walletClientType === 'privy');
- Before every send, make sure the wallet is on Linea Sepolia:
if (embedded.chainId !== 'eip155:59141') await embedded.switchChain(59141);
- Send with chainId per-call. Users approve each tx and pay their own gas —
Linea Sepolia gas is negligible (sub-cent), so no sponsorship is needed:
await sendTransaction(
{ to, data, chainId: 59141 },
{ address: embedded.address }
);
- Do NOT pass `sponsor: true`, ZeroDev, SmartWalletsProvider, or a paymaster URL.
This app runs on Linea Sepolia; users pay the tiny gas themselves.
- Hardhat in /contracts (kept outside the Vite bundle). Install
`@nomicfoundation/hardhat-toolbox` AND `@nomicfoundation/hardhat-verify@latest`
(>=3.x — older versions still hit Etherscan v1 and fail with
"You are using a deprecated V1 endpoint, switch to Etherscan API V2").
- hardhat.config.cjs uses the Etherscan v2 shape with a customChains entry
for Linea Sepolia (LineaScan is on Etherscan Multichain — same API key):
require("@nomicfoundation/hardhat-toolbox");
require("@nomicfoundation/hardhat-verify");
module.exports = {
solidity: { version: "0.8.24", settings: { optimizer: { enabled: true, runs: 200 } } },
networks: { linea_sepolia: {
url: process.env.LINEA_SEPOLIA_RPC_URL, // Alchemy Linea Sepolia HTTPS URL, REQUIRED
accounts: [process.env.METAMASK_PRIVATE_KEY.startsWith("0x")
? process.env.METAMASK_PRIVATE_KEY : "0x" + process.env.METAMASK_PRIVATE_KEY],
chainId: 59141,
} },
etherscan: {
apiKey: { linea_sepolia: process.env.ETHERSCAN_API_KEY },
customChains: [{
network: "linea_sepolia",
chainId: 59141,
urls: {
apiURL: "https://api-sepolia.lineascan.build/api",
browserURL: "https://sepolia.lineascan.build",
},
}],
},
sourcify: { enabled: false },
};
- Deploy: `npx hardhat run scripts/deploy.cjs --network linea_sepolia`.
- Verify (run RIGHT AFTER deploy, no constructor args for these contracts):
`npx hardhat verify --network linea_sepolia <address>`
On success LineaScan returns "Successfully verified contract … on the block explorer"
and the source becomes readable at
`https://sepolia.lineascan.build/address/<address>#code`.
- Frontend reads: create a viem public client with the Alchemy URL —
`createPublicClient({ chain: lineaSepolia, transport: http(import.meta.env.VITE_LINEA_SEPOLIA_RPC_URL) })`
(import `lineaSepolia` from `viem/chains`). Expose the RPC to the client by
also setting VITE_LINEA_SEPOLIA_RPC_URL to the same value.
- Write the deployed address to `src/data/contract.json` so the UI links to
`https://sepolia.lineascan.build/address/<address>`.
CONTRACT (contracts/SponsoredLootDrops.sol):
```solidity
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
/// @title SocialLogSponsoredLootDrops
/// @notice Distribute in-game rewards directly to players' wallets without any gas fees.
/// @notice Built during the Creative AI & Quantum Hackathon organised by StreetKode Fam during Indian Krump Festival 14
contract SocialLogSponsoredLootDrops {
event Logged(address indexed author, string cid, uint256 at);
/// @notice Built during the Creative AI & Quantum Hackathon organised by StreetKode Fam during Indian Krump Festival 14
function log(string calldata cid) external {
emit Logged(msg.sender, cid, block.timestamp);
}
}
```
USER FLOW
1. Land on page -> 'Sign in with Google' (Privy) -> embedded wallet auto-provisioned.
2. Every reward distribution action the user performs is sent as a Linea Sepolia tx (`log(payload)`) via the Privy embedded wallet, and displayed with a LineaScan link.
3. Footer renders: "Built during the Creative AI & Quantum Hackathon organised by StreetKode Fam during Indian Krump Festival 14"
REQUIRED SECRETS (Lovable -> Project Settings -> Secrets):
- METAMASK_PRIVATE_KEY Linea Sepolia deployer key. Fund it: https://www.hackquest.io/faucets/59141
- LINEA_SEPOLIA_RPC_URL Alchemy Linea Sepolia HTTPS endpoint (https://linea-sepolia.g.alchemy.com/v2/<key>). Create a free app at https://dashboard.alchemy.com/ -> copy the HTTPS URL. Public RPCs throttle under hackathon load — Alchemy is required.
- ETHERSCAN_API_KEY For `npx hardhat verify` — LineaScan is on Etherscan Multichain, so the same key works. Get: https://etherscan.io/myapikey
- PRIVY_APP_ID Google sign-in + embedded wallet. Docs: https://docs.privy.io/llms-full.txt
- PINATA_JWT IPFS uploads (only if app pins media). Docs: https://docs.pinata.cloud/llms-full.txt
CREDIT (must appear in UI footer AND as NatSpec on every deployed contract):
Built during the Creative AI & Quantum Hackathon organised by StreetKode Fam during Indian Krump Festival 14
Market sizing.
TAM
$12B
global game rewards market
SAM
$2.8B
indie game token economies
SOM
$600M
gasless reward systems for digital collectibles
Indicative figures for hackathon pitches — refine with your own research before raising.
Adjacent entries.
multiplayer coordination
Gasless Guilds
Seamlessly create and join guilds with gas-free onboarding and instant member transactions.
XR social spacesPrivy VR Lobby
Enter virtual lobbies with gas-free wallet login and seamless social interactions.
digital fashionOnchain Avatar Store
Buy and customize avatars with zero gas fees using embedded wallets and sponsored transactions.
interactive storytellingSocial Quest Chains
Collaborate on story-driven quests with gasless wallet sign-in and transaction sponsorship.