Bitcoin XT

Bitcoin XT is an altcoin authored by Gavin Andresen, and Mike Hearn that notoriously attempted an attack on the Bitcoin network by attempting a coordinated denial of service on the Bitcoin network and exploit of low security wallets.

Originally Mike Hearn started the XT project as a mechanism to institute changes he felt were necessary in the p2p network but the Core project refused to integrate due to their drawbacks. When Gavin Andresen resigned as Core project maintainer, he moved towards a stance that Core needed to alter the consensus logic in a controversial way and restructure its decision making process along various lines that were roundly rejected by the entire Core development team.

XT proposed a philosophy of top down leadership from a single individual, in contrast to a consensus based approach taken by Bitcoin Core. Further, centralization of the network and weakening of no-trust guarantees was seen as an acceptable loss in the name of main-stream appeal. These radical positions hurt XT's chances to gain wide appeal, its development team failed to attract any Core developers, and it slowly lost the small amount of traction it had by virtue of its well known founding members.