When I started making the enemies for this game, I was trying to glean insight from more experienced developers talking about it. One thing the developers of Slay the Spire said stuck in my mind especially. They designed their enemies (especially elites and bosses) to pose challenges for certain deck constellations. So if, say, your deck's success rests mainly on being able to play 20 cards per turn, you'll have a more difficult time beating the time slug boss, because it automatically ends your turn after you played 12 cards.
Crystal Scorpion
With that in my mind, I had a couple of ideas how to make enemies more interesting than just having them attack and block with different strength. One such enemy is the scorpion (internally called 'crystallizer', since the scorpion sprite is likely one I will exchange later on). 
It has the 'crystal' stat which negates the first piece of attack damage it receives during a turn. So if your dice have a lot of species with high attack value (and high cost), you are at a disadvantage here. You kinda need a low-cost/low-attack species to waste in order for the scorpion to lose its crystal status and then attack with more power.
That however also seemed to be a bit too one-dimensional, so I added another wrinkle: every time the scorpion loses its crystal status, it permanently gains x amount of strength - making its subsequent attacks more dangerous to the player. Now a player has to weigh their options and could benefit from choosing not to attack at all in a turn if they haven't enough suitable attack species lined up in their roll.
There is an 'optimal' (I think) strategy though that players can discover (if they have the right species): you can simply focus on defending each turn and never attacking while loading up your characters with passive stats like "poisonous" or "thorns" that harm the scorpion when it attacks a character. This type of damage does not trigger a loss of the crystal status and the scorpion's attacks remain fairly manageable.
Now if the scorpion was a boss or elite enemy, I would likely have to add something to lessen the effectiveness of that strategy (like slowly increasing its strength over time, so you can't just drag out the fight infinitely). But for now, it is a common enemy and I'm happy with the challenge it poses.
Mutated Oak/Bug Symbiosis
Another decision the deckbuilder genre (and for that matter most RPGs and strategy games as well) often puts in front of the player is: who do I kill first? (always kill the medic first, right?) In the context of the story of Life Altered it seemed to make sense in form of a symbiosis between two enemies. Thus the oak and bug combo as an elite enemy encounter came to be.
The oak is the bigger immediate threat to the player because of its high attack strength and multi-attack capability. The bug on the other hand doesn't attack at all. It merely gives 10 shield to itself and the oak each turn and also provides a strength boost to the oak as long as the bug is alive. The bug cannot live without the oak, but the oak will stay (although weakened) when the bug is dead.
I was a little bit unsure of this combo. I was half expecting that every player would immediately focus on the bug and then turn to the oak which in my mind was the correct strategy. But early playtests have so far shown that there are players who focus on killing the oak and were still successful in their attempts. So for now it's a keeper.
Mindblocker Wolf
Ok, one more. This is visually my favorite so far (credit to @rkagst):
The mutated wolf has the 'mindblock' ability which prevents it from being targeted by one character each turn (the ability rotates to blocking another character each round). This is designed to make the player use the party-based deck system in a sensible way. I was worried that players might just over-use one of their three characters and only add to one set of dice and only evolve the species of that character. Which might be a viable strategy of course, but not really how I would want the game to played (although I am trying to restrain myself from dictating how the game is 'supposed' to be played).
And you can still use that strategy, because the mindblocker will only block your favorite character for one out of every three turns. But you'll have to adapt slightly in those rounds.
In later game stages however, when the ascension system is unlocked, I do plan to make the mindblocker tougher by blocking two players instead of just one. That seems fair, right?
That should be enough for now. I can explain my thoughts behind some other enemies in a future post maybe.
Progress report for September 2025
The demo has been out on itch and GX Games for a while now and if you've followed me on any of those platforms, you will know that I have made a couple of bugfixes and adjustments to that demo based on the feedback that I have received so far. This has been an incredibly gratifying and helpful process for me and I have spent most of September trying to improve the quality of the demo. This will continue in October, but I'll also try to add a little new content as well (some new species, abilities, enemies and events). I think I have gotten the demo fairly stable for now and would like the next update to be a bit bigger than the previous ones, but we'll see how much work I'll get done (things are a little hectic right now).
Oh, and since yesterday Life Altered is being featured on GX Games which has gotten me over 1.000 new players in one day, so hooray for GX games!
I am still quite a bit away from feeling comfortable to releasing the demo on Steam, but I'm inching closer. If in the meantime you want to check it out:
You can either play it in your browser on GX Games:
https://gx.games/de/games/80txcq/life-altered/
Or you can download the game from itch:
https://pychogames.itch.io/life-altered
Here are the release notes for the updates I made in September:
Version 0.1.3
Adjustments:
Buff Summoner Alien
Nerf Tea Plant (Increased Energy Cost)
Shorten animation time of rolling dice
Reduce time between events in the non-player-action battle phases
Add trail effect to projectiles
Bugfixes:
Game will no longer crash in certain situations when mousing over an enemy
Infected mouse will no longer show a wrong description in some cases
Infected Mouse will no longer cause crashes when loading during evolution process
Hyena is no longer displaying wrong damage previews
Arthropod eggs will now disappear when their host dies
Version 0.1.4
New content:
New skill (mammals): Stoat
New skill (plants): Cedar
Adjustments:
Energy cost indicator on the dice now looks like the energy orb
Added text to the team select screen, hopefully communicating that is a party based game
Improved the wording on a couple of dice effects
Lowered the cost of clover from 3 to 2
Characters who are eligible for a buff now flash green when you select that buff
Bugfixes:
Negative enemy attack strengths are no longer possible
Infected mouse will correctly appear in evolution preview boxes
Make tooltips appear for reward screen dice
Cost increase infection no longer stacks its effects with each roll
Game will no longer slow down or crash after multiple resets on the evolution screen
Dice description no longer appears for invisible die faces on the reward screen
Battles and events no longer repeat (every battle should now have a unique enemy and no event should repeat during a run)
Tool tips will now show correctly for evolved dice on the evolution screen
Mineralized scabs will corectly apply shield to all eligible characters, even when multiple characters are healed.
Opening the chart sheet no longer crashes the game if the player has no seeds in play.
It is no longer possible to create multiple arrows when chosing a new creature to add
Version 0.1.5
Adjustments:
Mousing over enemies will now explain their actions as well as their status symbols
Added volume control to options in main menu and in-game menu
Bugfixes:
Fix performance issues during battles
It is no longer possible to select the same die face for evolution and sacrifice
Pressing SHIFT or middle mouse button no longer ends the player's turn
Repeatedly pressing Escape or right mouse button on the camp/evolution screen does not cycle between evolution and camp/evo choice anymore
Oh and one more thing...
Someone recently made a nice Let's Play from the demo. The YouTuber was using an earlier version of the demo that was plagued by performance issues (I fixed those in later versions), but it's still a very nice video. Here it is, if you're interested: