Definitely, your rank should be based on the rank of the player you beat/lose to. Meaning, you rank up faster when you beat a higher ranked player, and downrank faster when you lose to a lower ranked player. This is how Elo* works.
*"Elo" is not an acronym, it's a man's name, so no all caps.
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Some good things have been said and shown of this game. However, based on my experiences, both with Team17 and other game companies, I'm still cautious, maybe even a little worried.
Example #1: MechWarrior Online (Piranha Games)
MWO is based on a tabletop game with a very nerdy following. Early in development, the team gave these hardcore fans every reason to believe that they were dedicated to making the game they wanted with balanced, deep, competitive gameplay. But as development progressed, these promises were pretty much thrown out the window. New features were added to appeal to casual players. The balance was out of whack, and instead of listening to the best players, the team kept adding bandages that fixed some things and broke others. This all culminated with the head of the company pretty much telling the hardcore fans to buzz off.
Example #2: Halo: The Master Chief Collection (Microsoft)
Prior to this re-release, the first Halo game (considered to be the most balanced) had never officially been online, and Halo 2 (with the most fondly remembered online mode) had been offline for some years. Together with Halo 3 and 4, these were promised to be ported just as they were to Microsoft's latest console, along with HD upgrades and new content. They talked a good talk during development, but actual game assets were sparse. When it launched, the online barely worked, the entire collection was replete with bugs, and Halo 1 and 2 were based on their inferior PC ports rather than the original, award-winning console releases. Management clammed up, some iffy bandages were applied, time-limited compensation doled out, and that was that.
Example #3: All 2D Worms games post-WWP
What makes WA so beloved compared to other Worms games can mostly be summed up in three points.
1. Fast, light, predictable physics.
Worms in WA are very easy to move around. Even a mere Bazooka or Grenade can throw them a good distance, and superweapons can blast them into the stratosphere. All of the 2D Worms games I've played since then have felt heavier, slower, and stickier. Aside from walking and jumping, worms simply don't move well. In addition, pulling off an attack is a chore.
In WA, everything is highly predictable. You would think this would harm complex strategy, but the variety of moves and maps available compensate fully. Newer Worms games still generally have good map and weapon variety, but it's rendered moot because the game wants to fight you every step of the way. Not ONCE have I been able to complete a full match without a tricky turn failing because some weird hitch happened, like like a worm stopping dead in it's tracks after a long flight, a worm barely moving after a huge explosion, a worm falling off an edge for no apparent reason, a grenade bouncing in a strange pattern, and so on.
The videos I've seen of WMD so far do seem somewhat looser than other recent titles, but still have some of that unpleasant flavour. Please show us that Team17 is dedicated to providing a loose, fast, and precise gameplay experience.
2. An unobtrusive, easy-on-the-eyes HUD and art style.
Clarity is key. Clear names, clear icons, clear numbers, clear what's happening on the map, under all conditions. WMD's visuals certainly look nice, but is it good for gameplay? Worms, objects, effects such as fire, and HUD elements need to contrast against the map/background, and be easily recognizable EVERY TIME.
In the videos I've seen, worms are an awkward shape, and sometimes blend into busy parts of the map. Fire is semi-transparent, and doesn't contrast well against its surroundings. And most egregiously, the fonts used, which appear similar (if not the same) to the fonts used in other recent Worms games, are thick and hard to read against some background elements.
It may not be too modern, but you never need to struggle to see WA's "black velvet" HUD.
3. Classic network interface.
Server browser. IRC. In-game chat. All standard until Halo 2's matchmaking came along and casualized online gaming. It's sorta ok for FPSes, but turn-based strategy? Without flexibility and communication, things can and will get boring REAL fast.
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I understand that you have a pre-determined marketing plan, but unless that plan is to continue on the same path of releasing forgettable titles, you need to show that you are truly, FINALLY going to put the very best of Worms into a new package.
Team17 prides itself on being small, independent, and a survivor - make the most of that!