Leet is a Tinker whose power lets him create inventions decades ahead of their time - he has access to all Tinker technology trees - but the closer a project is to something he's made before, the higher the chances of a spectacular misfire or failure. While his power's weakness absolutely makes him a laughingstock, when the things he makes work, they can do incredible things.
His passenger is actually working against him due to his tendency to play it safe putting him completely out of tune with it, purposely trying to mess him up and get him killed.
Once Tattletale figured out that the people responsible for stealing the Undersiders' money were still around, Leet clapped, drawing the Undersiders' attention where he and Über were standing. After Skitter covered their snitch with her insects, he asked her if that was necessary. He glared at Regent for insulting his Bomberman costume before hopping down to stand beside Über. He told Grue that Bitch had led them to the money, although he didn't say how they had found her.
Leet talked with Über about how they would proceed before the battle began. As Über the Undersiders, Leet pulled out a bomb. Regent made him drop it and he bolted, glaring at the other team after Über was blasted back by it. He defended his actions by saying their mission was worth it only to take a step forward as Tattletale continued to provoke him. He told her that he could make anything and threatened to demonstrate before he started to introduce their 'guest'. He was cut off when Grue blasted him in the face with a cloud of darkness.
↑Leet – Partner to Über, is a tinker without limits, except that the more similar an object is to something he’s created before, the more likely it is to misfire.--Basic Cast Page
↑Leet's biggest problem is that it took him time to figure out the 'rule' to his power. He tried a variety of things in attempts to work out what his specialty was, and he burned a lot of bridges. That's not a 'Leet' problem so much as a trap that a lot of people (including many here) would fall into. Word of God - he caught on faster than your average geek might.
Now, any time he sits down for a project, he has to cross-check against all the other things he ever made. This isn't end-product related, but works out to components. Example? Power source. He either uses something mundane, or he uses something tinker derived. But if he uses something tinker derived to power his newest project, then he has to think of all the other power sources he's used, make sure that this one is sufficiently different, gauge the risk, and then move forward. Same goes for the mechanisms, the overall design & goal, and so on.
Defiant has the 'tinker up efficiency/hybrid/minimized technology' skill tree. Stinger has the 'missile' skill tree. Tecton has the 'Seismic and Architecture' skill trees. Leet has all of them, but all throughout those trees are entire sections with 'Use of this technology has a X% chance to fail'. You get further away from one design, that chance drops, but it's still there.
The video game thing was partially personal passion and partially a means of 'categorizing' what he did. On top of a wealth of notes and reference documents, he can think back through the various games he's been inspired by and use that as a mnemonic device to recall what he did for each project.
So by the time you/he figure(s) out the 'catch' to the power, the list of options is riddled with fail chances. You know there are a few trees you've not explored yet, but you have to progress carefully. How? You weigh the odds, estimate your chances of failure, trust your one really reliable buddy/sidekick to cover your ass if something blows up, and you do lots of little jobs you can afford to fail until you have the resources to do one big job well with something you're ninety-five percent sure won't blow up in your face.
Except he can't really seem to catch a break. He doesn't know it, but he's basically doing the opposite of Jack Slash and Taylor. He's explicitly out of tune with his power, he doesn't nurture it the way others do, even by general conflict - he's a little too cowardly, a little too safe, in large part, because he's hedging bets as often as not, and it's an unsatisfied shard, more prone to cause chaos for him rather than set him up to pursue it. It's trying to actively disrupt or kill its host so it can move on to greener pastures.
To top it all off, yeah, he's annoying, generally unpleasant, and people don't tend to like him. Except for Über.
↑Über and Leet (Missing) – A thinker with the ability to be a master at anything he tries, and a tinker with the ability to build anything, the two only barely managed to be b-list supervillains with a video game theme.--Cast Page (In Depth)