The addition of an invisible monster that one has to waste time in a tech race to fend off rather than fighting other players just smacks of bad design.
That's because it isn't the design of the game. It's a premature hack to allow the player to have some competition until there's a real AI. It's purpose is to force the player to make strategic decisions so that we can determine what strategic tradeoffs are fun and interesting. It is not, and was never intended to be the final design of the game.
Also, it's not useful to think of it as "wasting time in a tech race rather than fighting other players" - as it stands, the monsters are your main opponent, and as it's not practical to develop a competent AI with the game in its current state, they will probably need to be taken as such for quite a while. Think of them as the impetus for your empire to expand and develop. In the complete game, the player will constantly be in a "tech race" and an "expansion race" and a "production race" with every other player. Introducing these "races" in some limited, temporary sense, is the purpose of these space monsters.
"Try to expand and develop your empire more effectively.", that comment has to be the most self serving thing I have ever read. This passive-aggressive dribble implies that you have to posses skill, rather than a pre-scripted race to a single tech to save one's self from oblivion; deus ex machina anyone?
I deliberately made the monsters so that defeating them would be difficult, and fully aware that it was too difficult without using unreasonable and cheap tactics, I made it much less difficult, a fact which you have now ignored for two successive posts. If you're serious about testing the game, and not simply bashing an old/much more difficult version for being too difficult (which was known to begin with), then please follow my advice and replace your buildings.txt file with the one to which I provided a link.
Exactly what I said, "NO feedback to the player!" everything just dies.
So to clarify, you're not getting the sitrep messages I described?
Every other monster or ship in the game is at least visible.
The monsters are not invisible unless your empire's detection is below a certain level. Increasing your empire's detection level by researching detection techs (Active Radar, Neutron Scanner, Sensors) will allow you to see the monsters. Neutron Scanner will be adequate to see the first monsters that come, but subsequent monsters may not be visible unless you have Sensors, depending on which species you're using.
Having been instrumental in the development (in a paid capacity I might add) of over 80 games, you might want to have a bit more humility when answering legitimate questions or taking advice.
Had you actually provided any advice, or even posed a single question for that matter, I would have been happy to receive it/answer them with humility. However, all you've done is point out known facts about the difficulty of the game, some of which are no longer current. My response was to inform you that there already exists an adjustment to the game which makes it significantly easier, and that there is in-game content which solves one of your observed problems (that of invisible monsters). If you insist on not taking my advice and continuing to test an outdated version of the game, then "develop more effectively" really is the only response I can give you.