(Prepending edit:)
Is it supposed to be that you can melee with space or bumping?
Given the chaotic nature of the movement it's difficult to melee by bumping.
Yes, if you equip the knife, you can melee with space, otherwise you can just bump enemies to knife them, regardless of the weapon you have equipped. I'm not sure how to handle it being hard to bump them accurately -- the real-time nature of the gameplay means you tend to run around them part of the time, especially if they just moved, since then you'll just move into the space they were previously occupying. From a developer's perspective, I feel this needs work. From a player's perspective, I'd suggest equipping the knife and actively holding space when you want to knife zombies up for now.
I haven't worked on the game yet this week, taking a break to do other things. I spent a day preparing and paying state and federal taxes, another day updating my resume and looking into temporary contract design work, and the rest of the week so far trying out the roguelike Cataclysm. I always find it disheartening to see another game do what I'm trying to do better than I've done it so far -- especially when it's a casual not-for-profit game. Which is to say that Cataclysm is great in some dimensions, and anyone excited about what I'm doing should try it out, if you haven't already.
Cataclysm captures a lot of good things in the post-apocalyptic survival genre. Scavenging in that game is extremely satisfying. The dual weight and volume limits work remarkably well to prevent packrat syndrome. Your strength determines how much weight you can carry without becoming encumbered, while your clothes determine how much volume you can carry, with your hands as a free slot that doesn't take up space. Wear cargo pants, a backpack, and a messenger bag to get copious carrying volume, but don't expect that to let you carry four heavy guns and still run quickly if you're too noodly to handle the weight. This forces you to focus on things that really matter, leaving behind guns, food, books, and craft supplies that aren't immediately useful to you, often returning to the same abandoned store multiple times as your needs change.
The clothing system is very impressive. It's flexible, realistic, and easy to understand. Each article of clothing covers a certain part of the body, and has an encumbrance value which reduces your performance using that part of the body. Wearing a backpack increases your torso encumbrance, while wearing steel-toed boots increases your feet encumbrance. Most items can be stacked freely, but stacking similar items adds additional encumbrance penalties (two pairs of pants worn simultaneously will encumber much more than the individual items would indicate -- an intuitive result for anyone who has layered up in cold weather). Some items, like shoes or a helmet, can't be stacked at all.
One of my favorite features is books. My sense in any post-apocalyptic scenario is that books become invaluable. After civilization collapses, the various skills and knowledge needed to carry on with daily life won't match up well with what the survivors have been practicing throughout their lives. A crazy survivalist may already know all about repairing radios, growing potatoes, and cleaning firearms, but a computer programmer probably won't know any of those things, and may not find anyone who does. Without power, the Internet's infrastructure of networked servers will vanish in a puff of smoke, and knowledge about how to maintain and reproduce the artifacts of civilization will be preserved only in books. Cataclysm contains libraries full of books. The novels are entertaining and improve your character's mood, but the real treasures are the non-fiction sections. From cookbooks to informative magazines to college textbooks, a large number of skills can be trained up by just reading the appropriate books. A lot of your skill gains won't come from practice, but from sitting down in libraries.
I don't love everything about it; Cataclysm is ASCII-based, and while that might not bother the majority of roguelike fans and people on this forum, my own hand-made graphics give my game a huge leg up on that count. Another thing that bugs me about Cataclysm is the scale. Streets are so gigantic that road stripes are twice the width of a person, and you can stand in the middle of a street and not see the buildings on either side. I mean, wow. I know why that happens -- Cataclysm's map architecture requires streets to be the same width as grocery stores, and he wanted stores to be big enough to have lots of shelves, but that explanation doesn't make it less strange. It's certainly something you can get used to after playing a few times, but I think the game would benefit noticeably from being scaled down by a factor of 2, so every 2x2 block becomes a single tile. This would also somewhat reduce the need for the game's most annoying feature, the kludgey Run/Safe mode, which freezes input when you see a monster. It's incredibly annoying, but is used to prevent you from getting instagibbed while holding down a move button to travel long distances.
Cataclysm is far from complete and new features are being added all the time, but I don't feel too threatened by it. Instead, I see its popularity, and some of its features, as an inspiration. I'm interested in other ideas people have about things one should be able to do in a post-apocalyptic survival game. What would you miss if I overlooked it? What would make a survival game feel awesome?